Issue link: http://read.dmtmag.com/i/859318
Transmission Fluids Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Important Transmission Fluid Properties Getting power from the engine to the drive track or wheels is the job of the transmission. e key to effective power transmission performance and long component life is proper transmission fluid selection. An understanding of transmission types, transmission fluids and OEM recommendations is important for maximizing transmission performance. Transmissions can be grouped into the following types: automatic, powershi, hydrostatic and manual. Each transmission requires uniqiue lubricant properties. Transmission Fluids and Friction Each type of transmission fluid has specialized formulations to create frictional properties that ensure proper operation of the automatic, powershi or hydrostatic transmission it is protecting. In some instances, friction modifying additives are added to a base stock to make a lubricant more slippery. Of these fluids, the most friction-modified fluid is engine oil. As the evolution of transmission and transmission fluids progresses, some transmissions lubricated by engine oils may result in relatively poor transmission performance and holding capabilities, as well as increased wear. With automatic transmission fluids, TO-4 fluids and tractor hydraulic fluids, there is both dynamic and static friction measurements. Static friction refers to how well the transmission fluid will hold once lock-up has been achieved. Dynamic friction refers to the amount of slippage a transmission fluid allows before lock-up occurs. A balanced base oil and additive package for a transmission fluid is dependent upon the role the finished lubricant must play in the transmission. A typical transmission fluid must perform several critical functions: • Lubricate gears, bushings and bearings; • Provide anti-wear performance; • Displace heat efficiently; • Ensure seal performance; and • Modify frictional characteristics in transmission clutches and wet brake systems. Formulating a premium transmission fluid begins with a high quality base oil. e base oils must provide oxidative resistance and high and low temperature performance in order to ensure transmission fluid performance. e measure of a base oil's ability to resist oxidation or breakdown due to high temperature and severe service is related to the amount of saturated hydrocarbon molecules it contains. Group II and Group III base oils are treated with hydrogen to saturate the molecules and eliminate opportunities for oxygen to attack and break down these molecules. is process fills spaces in the hydrocarbon molecule that might otherwise fill with oxygen, with hydrogen atoms. is makes the base oil oxidation resistant, which is important to transmission fluid performance. D2 ecastrof