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3 Indicators to Determine Whether Hydraulic Oil Has Darkened and Deteriorated and Needs Changing in Summer The common hydraulic oil maintenance in summer is that the hydraulic oil darkens; does it need to be changed? Why is hydraulic oil easily darkened in summer? The truth of hydraulic oil darkening is oxidation. High temperature is the oxidation accelerator. The rate of oxidation doubles for every 10°C rise in temperature. The working temperature of hydraulic oil is commonly at 60-70°C, the open-air equipment even over 80°C, and the oxidation rate of mineral-based hydraulic oil is 4-6 times higher than in winter. The oxidation products are dark-colored gums and sludge, which is why the oil appears to have turned black. The metal particles generated by wear in the hydraulic system are oxidation catalysts. The more contaminated the fluid becomes, the faster the oxidation is, and create a vicious cycle. That’s why hydraulic fluid seems to darken increasingly rapidly once it starts turning black—it is not an illusion, but the result of accelerating chemical reactions. To determine whether an oil change is necessary, consider these three indicators: Indicator 1: Total Acid Number (TAN) TAN is the most direct parameter for measuring the oxidation level of hydraulic oil. New oils’ TAN is typically at 0.05–0.1 mgKOH/g. When the TAN increases above 0.5, it indicates the oxidation is significant. While it exceeds 1.0, the hydraulic needs to change necessarily. Why is TAN important? Acidic substances generated by oxidation will corrode the hydraulic components, especially for the copper valve spools and seals. Many instances of "valve sticking" stem not from poor valve quality, but from excessive acidity and failure to change the oil in time, causing the spool to seize due to corrosion. Indicator 2: Moisture Content High humidity and significant temperature fluctuations in summer intensify the hydraulic system's "breathing effect," causing the reservoir to draw in moist air and leading to condensation mixing with the oil. Even trace amounts of moisture (0.05%–0.1%) will reduce oil film strength and accelerate additive hydrolysis. If the moisture content exceeds 0.2%, dehydration or an oil change is necessary. Indicator 3: Particle Contamination Level Hydraulic oil turns black partly due to the suspended carbon particles and metal wear debris. According to the ISO 4406 standard, new oils’ contamination level is typically within the 18/16/13 range; if contamination levels rise above 22/20/17, it shows the filtration system has failed or that wear is accelerated, requiring an oil change or enhanced filtration. Recommendation: Change oil from mineral oil to synthetic hydraulic oil Compared with standard 46 mineral hydraulic oil, PAO-based 46# synthetic oil offers 3-5 times the oxidation stability as mineral oils. The TAN increases much more slowly during high summer temperatures, and the oil change interval is extended from 2,000 hours to over 4,000 hours. Although synthetic oil is more expensive, the saved costs on labor and reduced downtime losses far outweigh the price difference. Don't wait until the oil turns completely black before thinking about changing the hydraulic oil. The pump may already be worn out. Regularly monitoring acid value, moisture content, and particle count is the truly cost-effective maintenance strategy.

Below -25°C, the viscosity of hydraulic fluids becomes the variable that determines whether equipment starts or sits idle. Oil that flows fine at room temperature can restrict pump flow enough to load motors, starve cylinders, and generate contact wear — all before the system has had a chance to warm up. It's a failure mode that shows up reliably on Arctic construction sites, offshore deck systems, and in underground mining operations, and it's the problem PMA viscosity index improvers are built around.   PMA's performance across temperature ranges comes from how its molecular chains respond to heat. At low temperatures, the chains contract and contribute minimal viscosity of their own, letting the base oil flow freely. As the system warms, those same chains uncoil and thicken the oil, maintaining the film strength that protects pump internals and valve seats. Olefin copolymers can provide adequate high-temperature thickening, but their low-temperature performance typically falls short. With PMA, that tradeoff largely disappears.   Certain PMA grades crystallize around nascent paraffin wax as it begins to precipitate — blocking the large interlocked structures that gel the fluid. In a Group II base oil with a native pour point of -18°C, a 1.5% PMA treat brings that down to -43°C. When pre-heating isn't an option and a cold start has to work the first time, that 25-degree shift is the margin that counts.   Shear stability is where the test data gets specific. KRL (20h) SSI around 49% and diesel injector (30 cycles) SSI below 4% on commercial PMA grades indicate the oil holds its viscosity grade across extended service — relevant when drain intervals are long or field top-up is difficult. Not every VII performs consistently across both test methods. PMA tends to.   Chorus Chemical's T602HB puts a figure to each of these properties: 18.9 mm²/s kinematic viscosity increase at 100°C from a 10% dose; pour point down to -43°C at 1.5% in Group II base stock; KRL SSI of 49. For cold-climate hydraulic formulation, a single additive that covers viscosity index, pour point, and shear stability in the same treatment simplifies the blend and cuts cost — a practical argument, not just a performance one.  

Zhengzhou Chorus Lubricant Additive Co., Ltd. is a professional lubricant additive manufacturer and supplier in China. Chorus participated in the Shanghai International Lubricants Expo from June 9-11, 2026. Chorus shows its respect to every customer and provides excellent, selective solutions for lubricant additives. Featured products: lubricant additive packages, Extreme Pressure (EP) anti-wear additives, rust preventive inhibitors, polyalkylene glycols (PAG), synthetic ester base oils, and other lubricant additives. Chorus showed lubricant additives, metalworking fluids, and other related additives, including PMA-type pour point depressants, high-molecular-weight polyalkylene glycols (PAG) for quenching, and synthetic ester base oils. Polymethacrylate (PMA) pour point depressant offers excellent pour point reduction and good shear stability. It is suitable for engine oils, gear oils, hydraulic fluids, and other lubricants. With the excellent shear stability and low viscosity, PMA-type pour point depressant (PPD) can be widely used in various lubricant oils. The High Viscosity Water Soluble PAGs are used as a thickener in HFC fire-resistant hydraulic fluids. They are also used in metal quenching fluids and metalworking fluids. PAG (Polyalkylene Glycol) is used for quenchants combine the high cooling capacity of water and the safety and uniform quenching characteristics of oil and has the advantages of excellent quenchant performance, safety and environmental friendliness. Chorus provides a variety of synthetic ester base oils for lubricant applications, including engine oils, hydraulic fluids, aviation lubricants, compressor oils, chain oils, gear oils, and other industrial lubricants. Our synthetic ester base oils feature excellent oxidation stability and thermal stability, good low-temperature fluidity, high viscosity index, and outstanding biodegradability. In addition, we supply other lubricant additives and additive packages, such as gear oil additive packages, viscosity index improvers, and antifreeze corrosion inhibitors. Contact us for more information and the latest price.

Using a single type of cutting fluid across the entire plant may seem like a way to save on procurement costs, but in practice, the tool wear, surface defects, and shortened fluid sump life far outweigh the savings. The different materials have distinct differences in the cutting fluid. Choosing the wrong cutting oil is not just a matter of making do, but leading to more losses. Aluminium alloys: They are vulnerable to adhesion, corrosion, and discoloration. Main questions: the materials are soft and prone to sticking to the tool, which compromises the surface finish. Requirements: using the cutting fluids only for aluminium cutting oils (pH 8.0-8.5). The cutting fluid for aluminium should contain aluminium corrosion inhibitors to prevent discoloration or white spotting. The semi-synthetic fluids are superior to fully synthetic ones. Common mistake: using cutting fluid for steel that leads to surface staining.    Stainless steel: It’s vulnerable to hardness, heating, and cold welding. Main questions: stainless steel has a poor thermal conductivity and strong work-hardening tendencies. If the cutting zone’s temperature is over 600 ℃, the common cutting fluid can not form a useful lubricant film. Requirements: it should use extreme-pressure (EP) type cutting fluids, which contain sulfur, chlorine, or phosphorus additives. Or using high oil content emulsions or semi-synthetic fluids. The high flow flushing is more effective than simply increasing concentration.  Common mistake: using cheap cutting fluids to save cost, resulting in workpiece rust and frequently change cutting fluids. Therefore, the comprehensive cost is higher. Copper alloys: They are vulnerable to discoloration and spotting Requirements: the cutting fluid must be free of active sulfur and have a low oil or fully synthetic formulation. After operating, the copper alloys should be cleaned or coated with anti-rust oils. All in all, there is no universal cutting fluid. Aluminum alloys require low pH and corrosion inhibition; stainless steel requires EP additives and high flow rates; cast iron requires fully synthetic fluids with high chip-settling capabilities; copper alloys require sulfur-free, low-residue formulas. At a minimum, use two categories of fluid: one for aluminum and another for steel. Insisting on a "one-size-fits-all" solution saves money on procurement but leads to losses in tooling, yield rates, and fluid sump longevity.

Can the HFC fire-resistant hydraulic oil be high non-flammable and good lubricant? It's a difficult problem for most hydraulic oil users. The disadvantages of traditional hydraulic oils. Owing to its strong fire-resistance, HFC hydraulic fluid has become the first choice of high temperature applications like metallurgy, and continuous casting machines. But the traditional hydraulic fluids has the following shortcomings: Poor lubricity: the traditional hydraulic oils' kinematic viscosity at 40 ℃ is only 43mm²/s (the mineral oil is about 68 mm²/s), which increases the wear. Unstable performance: once the water vapors or mixed with oil sludge, the hydraulic oils' viscosity change quickly, and clog the filter. High temperature failure: is easily to have a chemical reaction under high temperatures, causing the poor oil lubricant film stability. The much progress of hydraulic fluids technology. 1. Molecular-Level Lubrication Enhancement Technology Nanoscale Extreme-Pressure & Anti-Wear Agents: Four-ball test wear scar diameter reduced to 0.50–0.60 mm (compared to approximately 0.8 mm for conventional products). Intelligent Viscosity Regulation: Viscosity fluctuation range reduced by 60% in response to changes in water content. Composite Corrosion Inhibition System: Copper strip corrosion rating ≤ Grade 2; equipment service life extended by 30%. The cooperate formulation of fire-resistant and lubricant Core Composition Functional Innovations Proven Performance High Pure Ethylene Glycol Contains Vapor Phase Rust Inhibitor Provides Rust Protection Even In Unsubmerged Areas Special Additive Packages Incorporates Self-Healing Lubricating Molecules Plunger Wear (At 21 Mpa Pressure)<17 Mg Stable Aqueous Based Precise Ph Control: 9.0–11.0 Resists Stratification And Degradation For 10 Years User Field Trials A continuous casting machine at a steelworks shows the following results: Maintenance Costs Reduced: The replacement cycle for plunger pumps was extended from 6 months to 18 months. Energy Efficiency Improved: System pressure fluctuations were reduced by 15%, and hydraulic energy consumption per ton of steel produced decreased by 8%. Safety Certification: Passed the U.S. FM fire-resistance standard. Selection Guide Application: For high-pressure systems operating above 25 MPa, the HFC-46 type is the preferred choice. Key Specifications: Prioritize checking the Viscosity Index (≥160) and the Falex Friction Coefficient (≤0.08). Compatibility: When retrofitting existing systems, all residual mineral oil must be thoroughly removed (residual oil content must be <0.1%).

Fire-resistant hydraulic fluids are essential for systems operating near high-temperature environments in industries such as metallurgy, mining, and power generation. As industrial equipment faces increasingly demanding operating conditions, the growing emphasis on fire prevention and environmental protection has driven continuous improvements in the quality and performance of these fluids.   Current Classification of Fire-resistant Hydraulic Fluids: Synthetic Types 1. Phosphate Ester (HFDR) 2. Polyol Ester (HFDU) 3. Synthetic Hydrocarbon (HFDS)   Water-containing Types   1. Water-Glycol (HFC) 2. Water-in-Oil Emulsion (HFB) 3. High Water-based Emulsion (HFAE) 4. High Water-based Chemical Solution (HFS)   Key Properties of Fire-resistant Hydraulic Fluids: Fire Resistance Lubricity Corrosion Resistance Viscosity-Temperature Characteristics and Viscosity Stability Material Compatibility Safety and Environmental Properties Performance Comparison of Fire-resistant Hydraulic Fluids   Introduction to Common Fire-resistant Hydraulic Fluids   Water-Glycol (HFC)   Composed of water, ethylene glycol, lubricants, vapor-phase and liquid-phase rust inhibitors, anti-foam agents, and various other specialized additives, this fluid is a hydraulic medium with intrinsic fire resistance. It is primarily used in industrial sectors such as metallurgy, machinery, mining, and marine applications.   Phosphate Ester (HFDR)   Phosphate Esters offer the highest fire resistance, with a spontaneous ignition point exceeding 550°C. Even if ignited at high temperatures, the flame will not spread. It is mainly used as a fire-resistant turbine oil and within the metallurgical industry. However, it is expensive and difficult to dispose of due to environmental concerns.   Synthetic Ester (HFDU)   Synthetic Ester is biodegradable through soil microorganisms and is non-toxic.HFDU has a high viscosity index, excellent thermal stability, and minimal pressure, ensuring stable lubrication between friction surfaces. Widely applied in metallurgy, biomass power generation, and mining, it represents an ideal future choice for fire-resistant fluids. Its usage is increasing annually in line with growing global environmental awareness.   Chorus supplies a comprehensive range of flame-resistant hydraulic oils, including Water-Glycol and Synthetic Ester types. We can provide solutions based on specific application scenarios. Contact us to obtain the latest pricing and Technical Data Sheets (TDS).      

The failure of hydraulic systems is partly owing to the hydraulic oils, which are typically due to either failing to select a product in accordance with national standards or using a fluid whose viscosity is ill-suited to the specific operating conditions. This causes the normal wear, low working efficiency, or pump burnout and complete system shutdown.   The following are the core standards of the major mainstream hydraulic oils. L-HL hydraulic oil: it’s the basic hydraulic oil for anti-rust and anti-oxidant, with a viscosity index of over 80. And it’s suitable for low pressure and light load capacity under 7MPa. L-HM hydraulic oil: it is mainly used as an anti-wear hydraulic oil for industry, which is divided into common and high-pressure hydraulic oil. The common hydraulic oil’s viscosity index is over 85, and the high-pressure oil’s is over 95. It’s suitable for middle and high-pressure plunger pump and gear pump systems. L-HV low temperature hydraulic oil: it has a wide temperature application, with the viscosity index over 140, and the lowest pour point can reach at -39℃, it’s suitable for extreme cold working conditions with the temperature over -30℃. L-HS ultra low temperature hydraulic oil: it’s suitable for extreme cold areas, and the viscosity index is over 150, the pour point can reach at -45℃,it’s suitable for extreme cold working conditions with the temperature below -30℃. How to choose the suitable hydraulic oil? 1. System pressure: the system pressure under 7MPa choose HL, 7-14MPa choose HM common type, over 14MPa choose HM high pressure or the same grade HV/HS. 2. The pump type: The anti-wear requirements for vane pumps, gear pumps, and plunger pumps differ vastly. High-pressure plunger pumps must never be—even as a stopgap measure—filled with low-pressure HL-grade oil; doing so will inevitably result in burnout. 3. The viscosity matched the rotational speed:1500-5000r/min light load, choose 15/22# hydraulic oil, the middle and low load use 68/100# hydraulic oil. 4. Working temperature: internal working conditions use HL/HM hydraulic oil, extreme cold area use HV hydraulic oil, and extreme cold weather use HS hydraulic oil. 5. Fire non-flammable: metallurgy, casting, and forging: conditions involving proximity to heat sources use HFC hydraulic oil, and it prohibits mineral oil to replace it. 6. Guide hydraulic oil: Hydraulic guide synthetic systems use HG hydraulic oil. 7. Humidity environment: seaside, a high-humidity environment uses the anti-rust hydraulic oil.

As industrial equipment continues to scale up in size, operating parameters, and run cycles, compressors are being pushed into increasingly demanding conditions. Conventional mineral oils, limited by their irregular molecular structures and relatively high impurity content, do not have the efficiency and reliability expectations of modern machinery — they've become a genuine bottleneck in maintenance operations.  Synthetic ester-based compressor oils clean at the molecular level, are more heat and oxidation-resistant, and are increasingly the practical choice when operations require better efficiency and lower lifecycle costs. Thermal oxidation-induced oil degradation is one of the most common root causes of on-site failures.  In screw-type air compressors, mineral-based compressor oils are regularly exposed to operating temperatures of 80–120°C. Under these conditions, oxidative cracking reactions occur readily, generating sludge, lacquer films, and other degradation byproducts. These deposits accumulate on rotors, valves, and oil filters — restricting flow passages, impairing heat transfer, and pushing operating temperatures even higher. The result is a self-reinforcing cycle: Excessive heat triggers destructive oxidation, oxidation accelerates degradation, and degradation raises temperatures further.   Synthetic base oils are produced through deliberate molecular design and controlled polymerization, which gives them a regularity in structure and a purity that mineral oils simply cannot match. Key performance characteristics — high-temperature resistance, oxidation stability, shear resistance, anti-coking behavior, and low-temperature fluidity — can all be tuned to suit specific compressor operating requirements, addressing the constitutive​ limitations of mineral oil at the formulation stage.   Beyond performance, synthetic base oils can be supplied to meet oil service intervals and longer equipment maintenance cycles, reducing unplanned downtime and associated losses.  These properties have made synthetic base oils a real factor in how chemical plants approach compressor reliability and energy use — and they're pushing the lubrication field in a direction it needed to go: better performance, longer oil life, and easier-on-the-environment formulations.   Synthetic ester base oils are produced by the reaction of organic acids with organic alcohols, yielding base oils that contain ester functional groups. The structural diversity available in both the acid and alcohol components makes esters the most designable class of synthetic base oils — their properties can be adjusted across a wide range, which explains why they find application in such a broad range of formulations.   Polyalkylene glycol (PAG) synthetic base oils are derived from the polymerization of alkylene oxides and are characterized by ether linkages in their backbone. The carbon-to-oxygen ratio within the polymer chain governs their behavior: higher ratios shift the oil toward lower polarity and better compatibility with hydrocarbon fluids, while lower ratios increase polarity and water miscibility.  This tunability has increased​ their adoption across air compression, process gas compression, and refrigeration compression Industries. The increase in ​oxygen content in the molecular chain also helps good lubricity and wear resistance — PAG-lubricated surfaces develop stable lubricating films that reduce component wear and extend equipment service life.   The use of synthetic base oils in compressor lubricants is not just about performance metrics; longer drain intervals, reduced deposits, and lower energy consumption also translate into meaningful economic and environmental benefits over the service life of the equipment.  

The secret of metals' anti-rust: choosing the correct rust-preventive oil Why do the metal pieces rust after a few days of production? This is a thorny issue for many factories. Now, following Chorus, we will teach you how to choose a suitable rust preventive oil. The 3 killers in metal corrosion. Electrical chemical corrosion is the most common corrosion. In humidity environment, the metal surface is easily prone to forming mini-electricity. For example, if steel is connected with water and oxidation, the metal will corrode like an electrical leakage. In summer, the workshop is of high humidity, which is the reason why the metal surface rusts. Chemical corrosion: When contacting high temperatures or strong acids and strong alkalis, the surface is corroded directly. For example, during steel rolling, the high-temperature scale is a product of chemical corrosion. The invisible corrosion-hand sweater. The salts and acidic substances present in human perspiration can leave corrosive marks on polished workpieces—particularly on precision components. Tip: During the plum rain season, it is recommended to maintain workshop humidity below 50% and to wear gloves when handling materials. Metalworking fluids for anti-rust prevention. Different working processes need different anti-rust additives. Anti-rust additives types Suitable Scenarios  Functions Cutting fluids Turning, Drilling Operations Cooling + Lubrication, Reducing Tool Wear Drawing oils Stamping of Stainless Steel Cookware Prevents Tearing/Cracking Rust preventive oils Short-Term Storage of Finished Products Forms a Protective Film to Isolate from Air and Moisture   For example, a factory uses the food oil to replace the drawing oil for stainless steel basins stamping, resulting in product deformation. And after switching to a specialized extreme-pressure drawing oil, the defect rate plummeted by 70%. 1. Consider the Material: Aluminum components are prone to corrosion → Select fluids containing amine-based additives. Titanium alloys have poor heat dissipation → Require cutting fluids with superior cooling properties. 2. Consider the Process: High-speed machining (e.g., grinding) → Water-based fluids dissipate heat rapidly. Heavy-duty stamping → Oil-based fluids offer greater pressure resistance. 3. Cost-Saving Tip: Centralized fluid supply systems allow for fluid recycling; however, regular monitoring of pH levels and concentration is essential to prevent bacterial growth, which can lead to fluid degradation and failure.  

Lubricants are primarily composed of base oils and additives, with the base oil defining the lubricant's fundamental properties. Base oils are generally categorized into two types: mineral oils and synthetic oils. They differ significantly in terms of raw materials, production processes, and performance characteristics. This article provides a systematic comparison to help you select the most suitable lubricant for your needs. 1. Mineral Oil: Cost-Effective and Widely Applicable Raw Materials and Production Process​ Mineral oil is derived from crude oil through distillation, solvent refining, dewaxing, and hydrotreating. Traditional methods involve solvent refining and clay treatment, while modern production commonly employs hydroprocessing to enhance performance. Performance Characteristics​ Varied by Category: Group I oils offer moderate viscosity-temperature performance and limited oxidation stability. Group II/III oils, improved through hydroprocessing, exhibit better viscosity index and oxidation resistance, with Group III oils approaching the performance of synthetic oils. Advantages: Lower cost (typically 1/3 to 1/2 that of synthetic oils); good compatibility with most seal materials; mature production processes and stable supply chains. Limitations: Less suitable for severe operating conditions (high temperature, high pressure, etc.); shorter service life and more frequent oil changes; slow biodegradation, posing higher environmental risks in case of leakage. 2. Synthetic ester: High Performance and Extended Service Life Raw Materials and Production Process​ Synthetic oils are chemically synthesized from small molecules such as ethylene and propylene, derived from natural gas or petroleum. Main categories include: PAO (Group IV): Polyalphaolefin, the most common synthetic base oil. Esters, Polyglycols, etc. (Group V): Produced through esterification or ring-opening polymerization. Performance Characteristics​ Excellent Oxidation and Thermal Stability: Stable molecular structure resists oxidation and breakdown. Superior Viscosity-Temperature Performance: High viscosity index ensures effective lubrication at high temperatures and good fluidity at low temperatures. Improved Friction Properties: Strong oil film formation helps reduce energy consumption. Advantages: Suitable for extreme operating conditions; extended service life (drain intervals can be 2–3 times longer than mineral oils); lower maintenance costs over time. Limitations: Higher cost (typically 2–3 times that of mineral oils); potential compatibility issues with some seal materials; complex production processes and higher technical barriers. 3. How to Choose the Right Base Oil Choose Mineral Oil If: Operating conditions are mild, cost is a primary concern, and maintenance or oil changes are easily managed. Choose Synthetic Oil If: Equipment operates under high or low temperatures, heavy loads, or extreme conditions, or if extended oil drain intervals and reduced maintenance downtime are desired. Choosing the correct lubricant base oil not only ensures smooth equipment operation but also improves energy efficiency and reduces maintenance costs. Whether selecting mineral oil for standard applications or synthetic oil for demanding environments, matching the lubricant to the actual need ensures both economy and performance. For further assistance in lubricant selection or solving lubrication-related challenges, feel free to contact us. We are here to provide professional support.  

Approximately one-third of energy is consumed by friction, and annual losses resulting from wear amount to hundreds of billions of yuan. The piston wear accounts for about half of the engine's friction. In order to minimize metal-to-metal contact, using the friction modifier in engine oil is a very useful method. What are friction modifiers? Friction modifiers can reduce the friction coefficient, which can form a protective film under boundary and mixed lubricant conditions to improve lubricity and energy efficiency. The mechanism of friction modifiers The polar group in the friction modifier additives can form a protective film on the metal surfaces through physical or chemical adsorption, which can prevent the direct connection of metals to reduce friction and loss. The types of friction modifier additives: Oil-soluble friction modifiers: mainly include fatty acids, esters, amines, amides, phosphorus-containing compounds, borates, organomolybdenum compounds, etc.  Among these, molybdenum dithiocarbamate (MoDTC) and molybdenum dialkyldithiophosphate (MoDTP) are useful to reduce the friction coefficient, inhibit lubricant oil temperature rising, improve working efficiency, and lower energy consumption. Non-oil-soluble friction modifiers include molybdenum disulfide (MoS₂), graphite, tungsten disulfide (WS₂), boron nitride (BN), etc. The non-oil-soluble friction modifiers utilize their layered crystal structures to reduce frictional resistance. Chorus can provide you with organic molybdenum friction improver MoDTP-300 with excellent anti-wear, Extreme Pressure, & anti-oxidation ability that can improve loading capacity, mechanical efficiency, and reduce energy consumption. The following table is a comparison between organic molybdenum friction improver MoDTP-300 and other anti-oxidation additives. Anti-oxidation additive Friction coefficient Wear Scar Diameter/mm MoDTP 0.045 0.28 ZDDP 0.110 0.80 Tricresyl Phosphate (TCP) 0.090 0.55 Sulfurized olefin 0.120 -  

With the rapid development of modern industry and the increasing prominence of environmental issues, there are growing requirements for lubricants in terms of performance, operational reliability, service life, biodegradability, and low or non-toxicity. Traditional mineral-based lubricating oils can no longer meet these stringent demands. Synthetic esters exhibit the best overall performance among all base oils. The most significant characteristic of ester oils is the presence of multiple ester bonds (-COOR) within the ester molecules. This structure imparts polarity to the molecules, providing ester oils with many superior performance and application characteristics compared to PAO (polyalphaolefins) and Group II or Group III hydrocracked base oils. Application Industries of Synthetic Ester Base Oils 1. Engine Oils: Primarily diesters and polyol esters; others include polyesters, monoesters, phthalate esters, and dimer acid esters. 2. Two-Stroke Oils: Generally utilize trimellitates, complex esters, dimer acid esters, and polyol esters. 3. Compressor Oils: Generally utilize diesters and polyol esters; additionally, PAG (polyalkylene glycol) polyether base oils can be used. 4. Aviation Lubricants: Generally utilize diesters and polyol esters. 5. Fire-Resistant Hydraulic Fluids: Typically utilize trimethylolpropane (TMP) oleate and pentaerythritol (PE) oleate. 6. High-Temperature Chain Oils: Generally utilize diesters and polyol esters; additionally, PAG polyether base oils can be used.

Trimethylolpropane trioleate (TMPTO) is produced by the transesterification or esterification of trimethylolpropane (TMP) with oleic acid (OA). Industrial-grade products are usually colorless or yellow transparent liquids. The synthetic process of trimethylolpropane trioleate (TMPTO)   The features of trimethylolpropane trioleate (TMPTO) 1. High flash point (＞300℃): when the working conditions are under high temperatures, choosing the high flash point TMPTO is safer. 2. Low acid value: oil lubricant system like hydraulic oil need a low acid value, which is conducive to demulsification resistance. A water-based system can use the TMPTO with a proper acid value that facilitates emulsification. 3. Base value at 80-85 is better. When the base value is over 85, the TMPTO has a good low-temperature performance. But it’s easy to oxidize; you need to add antioxidant additives. When the base value is below 80, the TMPTO has a good anti-oxidation performance, but a poor low-temperature liquidity. Therefore, when choosing TMPTO, you need to consider the corking conditions. The practical application of TMPTO 1. The products synthesized by TMPTO have a higher demand for environmental protection. 2. TMPTO has good biodegradability, and it’s low and non-toxic, which can replace sulfurized lard and tall oil. 3. TMPTO has a higher lubricity that can improve the products’ lubricant performance and can satisfy the special demands of some fields. 4. To some extent, using TMPTO can prolong a product's life span. High flash point, low pour point, making TMPTO suitable for high temperatures. TMPTO has excellent performance, including excellent lubricity, high viscosity index (VI), good fire-resistance, and biodegradability of over 90%. It’s the ideal base oil for the 46# and 68# synthetic ester non-flammable hydraulic oil that can be used for formulating environmentally friendly hydraulic oil, high-temperature chain oils, engine oils for yachts, and other industrial metal working fluids.

With the upgrading of the manufacturing industry, new materials such as shape memory magnesium alloys, advanced titanium alloys, and high-entropy alloys, due to their advantages like lightweight, high strength, and high temperature resistance, have become the “new favorites” in fields like aerospace, new energy, and high-end equipment. However, the difficulty of processing these materials is surpass the traditional metals, which puts higher demands on metal working fluids. The customized demands of new materials for metalworking fluids. 1. Anti-oxidation and anti-corrosion are the bases: Materials like magnesium alloys and super stainless steel have extremely high requirements for "chemical stability". The metal working fluid should contain special corrosion inhibitor additives. For example, the magnesium alloy processing fluid should be able to form a protective film to avoid color change and fire risk. 2. Lubricity and cooling should be dual-line When processing titanium alloys and ultra-high strength steels, “heat” and “friction” are 2 major challenges. Titanium alloys have poor heat conductivity, so the processing fluid needs to quickly dissipate heat. At the same time, the metal working fluid should be a lubricant to reduce tool adhesion. The working fluid for ultra-high strength steel with high hardness should contain extreme pressure additives such as sulfur and phosphorus to reduce cutting force and extend the life span. 3. Compatibility with processes and environments For duplex titanium alloys for 3D printing, the processing fluid must be compatible with the printing raw materials and can not pollute the product. And in humid environments, the metalworking fluids should have a protective performance to avoid corrosion. For 3D-printed duplex titanium alloys, the processing fluid must be compatible with the printing raw materials and not contaminate the product; during high-temperature processing of high-entropy alloys, the processing fluid must not deteriorate at high temperatures; in humid environments, the processing fluid must also be able to prevent rust and avoid material rusting. 4. Environmental protection and safety are important New materials are mostly applied in high-end fields, so the processing fluid must have no harmful components and low volatility. It not only protects the health of operators but also avoids affecting the performance of the materials.  3 methods of choosing metalworking fluids 1. Choosing the metalworking fluids on the materials’ characteristics High hardness (high-end alloy, ultra-high strength steel)-choose the high extreme pressure cutting oil or high-concentration emulsion fluid Easy to oxidize (magnesium-alloys)-using the metal working fluids with anti-oxidation additives first Sensitive to thermal (titanium alloy)-emphasizing cooling performance, choose water-based cutting oils 2. matching with the processing Cutting processing, emphasizing lubrication and cooling, extreme pressure cutting oil or water-based fluid should be chosen as the basic metal working fluids. Grinding-emphasizing cleaning, avoiding clogs, and choosing high cleaning water-based grind fluids. 3D printed after treatment, choosing a highly compatible and clean working fluid. 3. Balance application and cost High temperature application: choosing the cutting fluid with high temperature stability Poorly ventilated workshop: choosing the low odor and low volatile cutting product. Choosing the right cutting fluid can improve efficiency, reduce cost, and can transfer the advantage into the products’ competitiveness.

Polyalkylene Glycol (PAG)is a type of polymer synthesized from alkylene oxides, characterized by low toxicity, good water solubility, excellent surface activity, as well as adjustable viscosity and lubricating properties. Its applications in lubricants mainly include the following areas:   1. Industrial Lubricants PAG is commonly used as a base oil for gear oils and high-temperature chain oils. It offers a high viscosity index, good extreme pressure performance, and low carbon deposit tendency. Suitable for heavy-duty gear systems in equipment such as textile heat-setting machines and plastic calenders, it remains stable at high temperatures and demonstrates good compatibility with rubber seals.   2. Compressor and Refrigeration Oils Polyalkylene Glycol exhibits good miscibility with refrigerants such as R-134a and possesses clean-burning characteristics, helping to reduce sludge and carbon deposits. With excellent lubricity, chemical stability, and low-temperature fluidity, it is widely used in automotive air conditioning and industrial refrigeration systems.   3. Metalworking Fluids​ PAG can form an effective lubricating film on metal surfaces, providing outstanding lubrication and cooling effects. It exhibits reverse solubility—soluble in water at room temperature but precipitating and adhering to metal surfaces when in contact with high-temperature tools, thereby enhancing lubrication. It is often used in fully synthetic or semi-synthetic metalworking fluids.   Zhengzhou Chorus specializes in lubricant additives, with Polyalkylene Glycol (PAG) as one of our flagship products. For applications such as gear oils, compressor oils, and refrigeration oils, we provide customized solutions that deliver cleanliness, cooling, lubrication, and environmental performance.

Do not add the 6 additives to cutting fluids. Prohibited additives: Nitrites Dicyclohexylamine Chromates Short-chain chlorinated paraffins (SCCPs) Additives subject to significant restrictions: Diethanolamine Formaldehyde-releasing biocides With the improvement of people’s awareness of environmental protection and the increasingly strict regulations, the ingredients of cutting fluids have changed a lot. Extreme pressure antiwear additive: For a long time, as the antiwear additive of the ingredient for cutting fluids, owing to the chlorinated paraffin having a carcinogenic risk, the aftertreatment will pollute the environment. The alternative to carcinogenic risk has been a new trend. Organic borate ester, as a lubricant additive, has the features of nontoxic, nonvolatile, and also has the functions such as rust prevention, antibacterial, and disinfection.   Organic borate ester is a special type of 2-ion surfactant substance and is widely used in cutting fluids. Rust preventive additive: Antirust additives can be divided into water-soluble additives and oil-soluble additives.  Water-soluble antirust agents react with metal and form a tough, insoluble oxidized film to prevent the metal’s electrochemical corrosion. The water-soluble rust inhibitors are usually electrolytes, and the dosage for emulsification is not too much. Because of its toxicity, expense, poor compatibility, and difficulty aftertreatment, it’s easily displaced in the future. Oil-soluble antirust additives are strong polarity compound, and can adsorb on the metal surface and react with the metal surface to form a protective film, inhibiting the connection of water, oxygen, and metals. All in all, molybdate is nontoxic and has no pollution, but it’s relatively expensive. Organic phosphorous contacting rust preventive additives have a certain corrosion to copper and its alloys. Low-phosphorus or non-phosphorus rust inhibitors are the main development trend. Antimicrobial and bactericidal agents Antimicrobial and bactericidal agents are generally used in water-based cutting fluids. By adding Antimicrobial and bactericidal additives, they can kill and inhibit microorganisms. In recent years, due to the increasingly strict environmental regulations, the commonly used phenolic and formaldehyde-releasing bactericidal agents have been restricted.

There are many surface active agents in lubricant additives, such as detergents, anti-foam additives, antirust additives, and some of them have multiple functions. The good surface active agent should have the following characteristics: Resistance to hard water: it’s a method to measure the emulsifiers’ resistance to hard water. Generally speaking, the traditional anion has a poor performance in this aspect; the cation is displacing them. Foams: in the lubricant oil, it’s widely believed that the less foam, the better. Therefore, we need to choose different types of emulsifiers and reduce the foam as much as possible. Biological stability: it’s the performance requirements of the emulsifier. In the long term, if the emulsifiers are eroded by bacteria, it’s harmful to the lubricant oil.   The increasing development of environmental protection has put higher demands for lubricant additives, and dealing with the recycled waste oil and industrial wastewater is an important measure of controlling lubricant oil pollution. Detergent dispersant additive The detergent additive in the engine oil can keep the inner engine clean, and inhibit the formation of absorbed ink, accumulate carbon, oil, and dirt. The commonly used detergent additives are Petroleum sulfonate, alkylphenate, salicylate, and polyisobutylene succinimide, and they all have a wide application. The main mechanism is making the particles and non-soluble substances distribute uniformly by means of diversification, adsorption, and emulsification, and form a micellar solution, which is helpful to prevent them from adhering, depositing, or blocking the oil passage and filter screen. Antifoam additive: Some oil-soluble surface active agents can be used as a lubricant anti-foam additive. The commonly used defoamers are divided into 3 types: anti-foam additives with silicon, non-silicon antifoam additives, and compound antifoam additives. The main function is to prevent the formation of air bubbles in the lubricating oil or to remove the formed air bubbles as soon as possible. The common silicon polymer is polymethylsiloxane defoamer for lubricants; a non-silicon antifoam additive is a mixture of synthetic hydrocarbons and polymer. The compound defoamers are usually a combination of the above 2 types of anti-foaming agents, having both advantages. Anti-rust additives Rust preventive additive can be used as the surface active agent, which is mainly water in oil. The common antirust additives are carboxylic acids and their salts, alkylbenzene sulfonates, nitrogen-containing amphiphilic molecules, and some phosphorus-containing compounds. The surface active additive also uses the lubricant emulsifier; it’s mainly used to reduce the tension between the water and oil surfaces, making them mix together and form a uniform dispersant system. Emulsifiers and antirust additives are the important role in lubricant oil. At present, the surface active agent is mainly used to promote the uniform spread of the oil, biodegradation, and dealing with wasted oil and water. 

Fire-retardant hydraulic oils are hydraulic media that are not flammable under high temperatures and open flame environments, which are mainly used for industries with high fire risks, such as metallurgy and die-casting, to replace flammable mineral oil and guarantee working safety. Among all the fire-resistant hydraulic fluids, HFC water-glycol fire-resistant hydraulic fluid is the mainstream non-flammable hydraulic oil in metallurgy. According to ISO 12922, fire-resistant hydraulic fluids mainly include: water-based fluids and synthetic flame-retardant hydraulic fluids. Water-based hydraulic fluids include: HFA (high water-based), HFB (oil in water), HFC (water-glycol Solutions ). The synthetic type mainly consists of HFDR (phosphate ester) and HFDU (fatty acid ester).   HFDR has excellent performance, but it may produce toxic substances under high temperatures. HFDU has a good comprehensive performance, but at a higher cost. HFC has the features of good non-flammability, lubricity, and proper price, which have a wider application. The reason why HFC water-glycol fire-resistant hydraulic fluids are the mainstream in the metallurgical industry is mainly displayed in the following aspects: 1. Comprehensive performance: HFC has a good performance on flammability resistance, lubricity, anti-rust properties, long service life, and economy, and it’s suitable for metallurgy and complex situations. 2. Good fire-resistance: HFC has a high water content of over 35-50%, the vapour will adsorb heat and form a vapour film to separate oxygen at high temperatures, which can prevent the flame efficiently. 3. Strong stability: the PAG thickener has a stable structure, and it’s difficult to water dissolve, and it’s not sensitive to water based system that can avoid the problem of emulsification and deterioration. 4. High viscosity index: the viscosity has a small change with temperature changes, which can guarantee the high temperature lubricity and maintain low-temperature liquidity. 5. Economy: Compared with synthetic ester and phosphate ester fluids, HFC offers a more advantageous price and can be used over a large span. For the cost of HFC non-flammability hydraulic oil. HFC is mainly formulated for water, glycol, and water-soluble PAG. The viscosity of PAG influences the dosage and performance directly; high viscosity PAG, like the viscosity at 75000, has a moderate dosage and balanced performance. The middle and low viscosity PAGs have a higher dosage; although the cost is lower, their performance is limited. The choice of compound additive also influences the pass rate of the bench test and the final cost. HFC fire-resistant fluid is suitable in high-temperature or open flame environments such as steel smelting, hot rolling, and coal mining, and can effectively reduce fire risk. With the development of metalworking and coal industries, the HFC fire-resistant fluid also continues to grow, making it the mainstream non-flammable hydraulic oil in the metallurgical industry.

HFC water-glycol hydraulic fluid is a fire-resistant medium specifically designed for hydraulic systems operating in high-temperature, high-pressure, and flammable environments such as metallurgy and underground coal mining. Its typical base composition includes approximately 40% water (providing fire resistance), 25%-45% glycol (for antifreeze and rust prevention), and a 3%-5% additive package.   The core performance characteristics of this fluid—viscosity, viscosity index, and lubricity—are primarily determined by the water-soluble polyalkylene glycol (PAG) thickener, which constitutes about 10%-20% of the formulation. The high ethylene oxide content in PAG grants it excellent water solubility and a high viscosity index, effectively maintaining system volumetric efficiency and extending pump life. The choice of PAG significantly impacts both performance and cost. High-molecular-weight PAG (e.g., PAG 75W-55000) offers high thickening efficiency with lower dosage but is more susceptible to viscosity loss under high shear. Lower-molecular-weight PAG (e.g., PAG 75W-18000) provides superior shear stability and longer service life but requires a higher concentration to achieve target viscosity, increasing formulation costs.   Furthermore, the additive package, making up about 3%-5% of the formula, is crucial for properties like rust prevention, foam suppression, and oxidation resistance. Given the high water content, selecting efficient and environmentally compliant rust inhibitors is key to ensuring long-term system stability and preventing corrosive damage.   Chorus supply various PAG thickeners and compounded additive packages, assisting users in finding the optimal balance between performance and cost based on specific operating conditions.

PMA viscosity index improvers in gear oils. The modern gear device is developing for high loading and high speed, which puts higher requirements for gear oil to keep stable viscosity in a wider temperature range.  Viscosity index improvers (VIIs) are the core lubricant additives to improve the gear oil’s viscosity temperature; they include PMA, OCP, HSD, and PIB.  Mechanism of viscosity index improvers. The viscosity index modifiers use the expansion and contraction features of high molecular polymer chains to improve the gear oil’s viscosity index. Making the gear oil has the low-temperature fluidity and high-temperature oil strength, and makes the lubricant stable in a wider temperature range. The special requirements of gear oil for viscosity index. Compared to engine oil, gear oil has higher requirements for VIIs. 1. Adhesion-enhancing ability: low dosage and good viscosity increasing performance. 2. Low temperature performance: ensure the smooth operation under low temperatures. 3. Shear stability: high shear stress resulting from the meshing of gears. 4. Oxidation stability: ensure a long life under high temperatures.   The choice of Viscosity index improvers Gear oil has the strictest demands for shear stability, especially for the viscosity index modifiers. The comparison of different viscosity index improvers. Thickening ability: HSD＞OCP＞PIB＞PMA Low temperature performance: PMA＞HSD＞OCP＞PIB Shear stability: PIB＞HSD＞PMA＞OCP Thermal oxidation stability: PMA＞PIB＞OCP≈HSD   OCP and HSD are not usually recommended for gear oil. PIB has a better high-temperature performance but a poor low-temperature performance. PMA has an excellent low-temperature performance, good oxidation stability, but poor shear stability.   When you choose the type of VIIs in gear oil should consider it carefully: in extreme cold areas, the PMA is better than the other 3 VIIs.