Transmission fluids

Transmissions are integral to any machine, manual or automatic. Without the proper fluids, your transmission will fail, and without a functioning transmission, your equipment is basically a huge pile of metal. While some manual transmissions now use automatic transmission fluid (ATF), most manuals use a variety of fluids for optimal engine and gear function. Gear oil isn’t the same thing as ATF, and knowing the differences can make or break your equipment. ATF Basics ATF is a complex fluid full of lubricants and detergents that keep the transmission running smoothly with minimal wear. Along with lubricant and detergent, ATF also contains a combination of additives including anti-wear additives, additives that block rust and corrosion, dispersants and surfactants that protect and clean metal parts in a transmission, kinematic viscosity and viscosity index improvers, seal swell additives that increase rotational speed and temperature range, anti-foam additives, anti-oxidation compounds, cold-flow improvers, high-temperature thickeners, gasket conditioners, pour point depressant, and some form of petroleum dye. To distinguish ATF from gear oil in a pinch, ATF is a much thinner fluid and is usually colored red or green. Gear oil basics Gear oil works to lubricate and prevent corrosion in a manual transmission. Because manual transmissions experience high friction during gear changes and clutch press-and-release, gear oil has additives of sulfur-bearing anti-wear compounds. This gives gear oil a distinctive, strong smell. Gear oil is also thicker than ATF because it serves mainly to lubricate the gearbox, transfer cases, and differentials. Incorrectly using ATF in a manual transmission or gear oil in an automatic transmission can severely increase the wear and tear. ATF does not have the thick lubrication qualities needed in a manual gearbox, and gear oil does not contain all the additives needed to smoothly run an automatic transmission.