Transmission cleaner for engines

[nissanracer300zx]

My friends car sentra has added transmission fluid instead of motor oil because someone told him transmission fluid would clean the inside of the engine deposits, and the car runs fine right now but is transmission fluid bad for the engine?

[ard]

hilarious...

[sultan]

it's fine as long as you just let the car idle or do some low rpm crusing for a short time. obviously this would be done right before an oil change because you can't drive with atf in the oil. the atf does clean/flush/whatever the motor.

just make sure your friend isn't replacing oil with atf, just add atf on top, run the engine a bit and then change the oil.

[mick]

Isn't "Mystery Oil" just another name for ATF? I used to put that in the crankcase and leave it.