Q: What Does Transmission Fluid Do?

Modern automatic transmission fluid (ATF) typically contains a wide variety of chemical compounds intended to provide the required properties of a particular ATF specification depending on the manufacturer.

Most ATFs contain some combination of additives that are required for there lubricating qualities,such as anti-wear additives, rust and corrosion inhibitors, detergents, dispersants and surfactants, which protect and clean metal surfaces kinematic viscosity and viscosity index improvers and modifiers, so your transmission fluid does not gel up or solidify in the winter. It also helps to seal by adding swelling additives and agents (which extend the rotational speed range and temperature range of the additives).

It also has anti-foam additives and anti-oxidation compounds to inhibit oxidation, as well as gasket conditioners and petroleum dye. All ATFs contain friction modifiers, except for those ATFs specified for some manufacturers transmissions that specifically exclude the addition of friction modifiers such as tractors and off-road vehicles.

There are many specifications for ATF, such as the Dexron and Mercon types (G.M. and Ford), which the vehicle manufacturer will tell you what the ATF specification appropriate for each vehicle. The vehicle’s owner’s manual will typically list the ATF specifications that are recommended by the manufacturer. The transmission dipstick will also have the fluid type imprinted on it if you do not have the owner’s manual.

The owners manual will also tell you when to change the fluid, it is very important to maintain the transmission the same way you would change your engine oil. Automatic transmission fluids have many performance-enhancing chemicals added to them to meet the demands of each transmission, no matter what you drive. So you cannot mix fluid types, no matter what the circumstances are.

If for some reason you have mixed the fluid types then get the transmission serviced right away to avoid costly repairs. Different manufacturers use different chemicals to meet the same performance specifications and ATF requirements. Always check your owner’s manual for this information. If you need assistance with this, have a certified technician help you with the transmission fluid change at your own convenience.