umakemekissu

Just being curious but serious at the same time. What would happen if a small amount (lets say 1/4 quart) of old transmission fluid accidentally filled to our transmission? How about old oil engine?

Note the amount is rather small does that make any difference?

Acura-OC

Transmission fluid into transmission? Yeah you are screwed.

KJ TL-S

iTrader: (9)

I cant imagine a bit of old trans fluid would cause a problem.

Old engine oil in your transmission you say tho? That doesn't sound like a wonderful thing, and I say that based on absolutely no true knowledge.

jpm3071

You should be ok. The biggest difference between engine and trans oil is trans oil has a cleaning solvent it. Ive even seen people do oil changes with trans oil for a few hundred miles to clean the motor. As long as its only a little bit you should be fine.

Acura-OC

Transmission fluid is a hydraulic fluid and motor oil is a lubricant. While transmission fluid does have some lubricating properties, it is not enough to sustain an engine.

Engine oil is designed to deal with the products of combustion,
whereas an ATF does not.

paperboy42190

iTrader: (7)

If in doubt, just do a drain and fill

Acura_Swag

If its a small amount i doubt it would do anything bad i woud say but im not too sure. But can we know how it happened?

truonghthe

it will double your WHP

umakemekissu

It was dark when I was doing a 1x3 transmission fluid change and somehow got my hand on a bottle contained old fluid I don't know whether it was old engine oil or transmission oil though...

I hate cars

A 20wt engine oil and ATF are similar in viscosity and even base oil. The main difference is the additive package including the red dye.

Engine oil compatibility depends on the brand. It has dispersants and detergents and contrary to popular belief ATF does not have more detergents. Both have friction modifiers but different types. Where you run into trouble is if the oil has moly in it. This is very bad for AT clutches and can cause slip. Engine oil will have a higher base number for dealing with acids caused by combustion so that's a plus even if its not needed.

Look up the oil you might have added and see if it contains moly or even high levels of zinc and phosphorus. If it does, change it out. If the trans shifts normally, the FM level is probably fine and you have nothing to worry about.