Thread: Can I use transmission fluid instead of engine oil? Read more: Can I use transmissio

It is recommend to not use transmission fluid in place of motor oil in a vehicle. Transmission fluid has a lower viscosity than motor oil, and manufacturers recommend an oil change if transmission fluid is added to the oil.

Whoda thunk it. Well . . .

Back in the day, when the Chevy Corvair was first introduced, I was working a just-out-of-high-school summer job at a gas station (In those days, that's what all red-blooded teenage males aspired to). The Corvair was a flat-opposed air-cooled rear engine car (think volkswagen with two more cylinders). When one pulled into the station, as a joke I told a less knowledgeable co-worker to check the water in the engine (glycol-based coolants wouldn't show up for another 10-15 years). Well, the next time I looked over, he'd removed the only cap he could find (oil cap), and filled the engine with water. Thit. That's not how I thought this would go.

When the car owner returned out of the adjacent store, I informed him what had happened, and that he'd get a free oil and filter change, then we pushed the car into the service bay and did it. As best I know, that customer never returned. That's what happens when you leave two teenagers alone and in charge. Glad the manager wasn't there at that time.

In a word... NO!

However, ATF is a better lubricant than most 'engine flush' products available, so if you just 'top off' your engine oil with a pint or so of ATF 50-100 miles before an oil/filter change, the fluid's added detergent properties will clean up engine internals nicely.

OTOH I'd bet that most here are using good synthetic engine oil already and probably don't have much, if any, buildup of gunk / flocculent deposits inside the engines. Personally, the 'ATF scrub' is a technique I reserve for used vehicles I buy that may have been sitting a while, or subjected to a lack of proper maintenance, or one that's 'recovering' from an episode of overheating.

ATF has to have a moderately-high level of detergency to keep the maze of passages and valves (largely electric solenoid-actuated today) in an automatic tranny’s valve body flowing properly, but it lacks the lubricity, thermal stability, and viscosity improver packages necessary for use in internal combustion engines.

BTW… Gary, the Corvair engine was designed on contract for GM by none other than Porsche, of course the founder of which developed the air-cooled Volkswagen. Not a ‘marriage made in heaven’: Porsche typically looks for Performance, and the Profits do follow. However, GM was only looking for Profits, and so was willing to compromise a fundamentally good design, with cheaper parts and execution, as well as Performance, to keep the bean-counters happy. That line of thinking is what really killed off the Corvair, and ultimately unleashed the Curse of the Vega and its Krappy Korporate Klones on the lazy-minded and fad-crazed American public. caveat emptor

YMMV

^ summed it up pretty well.


In general I wouldn't use transmission oil as engine oil but it can be done in an emergency.

Use engine oil, there should be no excuse as to why you can't get engine oil. Say if your burning oil and need oil ASAP, almost every gas station has oil you can buy.

It always pays to use the right thing!