Issue link: http://read.dmtmag.com/i/859318
Hydraulic Fluids Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Important Anti-wear Hydraulic Fluid Properties Ester base fluids Ester base fluids are synthetic base fluids containing oxygen in the molecule instead of just carbon and hydrogen like typical mineral oils. Most esters are readily (highly) biodegradable, and some have a high degree of oxidative stability as well. us, one can create an ester, which has the desirable combination of being highly biodegradable and oxidative stable. eir disadvantage is being significantly more expensive than mineral oils. PolyAlkaline Glycols PolyAlkaline glycols are used as synthetic lubricants in many diverse applications where petroleum oil-based products do not provide the desired performance – and because they are fire-resistant and will not harm workers or the environment. Other benefits of using PAG lubricants over petroleum, animal and vegetable oils is reduced energy usage, reduced machine wear and overall operational efficiency. Common Hydraulic Fluid Choices e following are the most common fluid choices for hydraulic equipment and some of the performance features of each: Anti-Wear (AW) Hydraulic Fluid Still the number one recommended fluid by pump manufacturers, a premium-performing AW hydraulic fluid should demulsify or clearly separate water from oil, protect against wear in the presence of water, maintain fluid viscosity and guard against oxidation. Fluids with a natural VI of 100 or more are better equipped to handle the extreme temperatures and pressures found in a hydraulic system. Properly formulated AW fluids usually provide excellent protection for hydraulic systems. It is important to note that hydraulic fluids with anti-wear additives that are not hydrolytically stable can become aggressive to yellow metal and cause premature failure in piston pumps. Excess water not removed from a hydraulic system will also accelerate vane and piston pump wear. Engine Oil Convenience has sometimes dictated the use of motor oils in the hydraulic sump. Motor oils emulsify or combine with water that has contaminated the system and may provide some protection from rust in wet, undrained systems. But, the anti-wear additives in motor oil are typically NOT hydrolytically stable when exposed to water. is can cause additive dropout in wet motor oil that can result in viscosity gain, pumpability problems and poor wear protection. Motor oil is designed for use in engine compartments where minor amounts of water are boiled off each day. A hydraulic system's operating temperature does not normally get high enough to boil off the water and the zinc compounds in the anti-wear additives can cause corrosive wear. Automatic Transmission Fluid (ATF) Like motor oils, ATFs emulsify or combine with water but are less aggressive when wet than motor oils. As a rule, the friction modifiers used in ATFs are not sensitive to water and tend to be thermally stable. In the past, ATFs have been a better hydraulic fluid choice than motor oil because of their oxidation resistance and solid wear protection. But, the latet passenger car specification, ATF Dexron®-VI, must meet performance specifications for extremely low temperature flow, which results in viscosities that are far too low for use in heavy-duty applications. C12 ecastrof