Difference between motor oil and transmission fluid

“I work at an auto parts store and customers ask the difference between motor oil and transmission fluid. What would your explanation be? Quick and simple –to the point.”

Tim McIlhenny, Bremerton, Washington


Motor oil is for your vehicle's engine. A couple of differences are the following: Motor oil is designed to deal with the products of combustion, whereas automatic transmission fluid (ATF) does not see contaminants from fuel burning. An ATF is basically a closed system and the lubricant must last for a long period of time. Motor oil must be drained to remove contaminants after a relatively short time and/or mileage compared to an ATF. Similar additive component types are used, but at different levels and different chemistries. In an ATF, clutch friction is a very important consideration. Transmission fluid is also used by your steering system to keep its parts moving smoothly.

Not finding the answer to a question like yours?