I mistakenl put gear oil in Chevy 02 pickup with automatic transmission

I regrettably poured a quart of gear oil in a 02 Chevy pickup automatic transmission. I did not drive the truck but I did run the engine. A mechanic suggested diluting it with paint thinner. Advice is greatly needed and appreciated. Thank you

Ignore that mechanics advice in the future. Have the transmission pan dropped, the filter replaced and the fluid flushed ASAP.

I am not a mechanic and I think paint thinner in the transmission is a dumb idea.

Drain it, fill it, short drive, drain, fill it, short drive, drain, fill it, drain, replace filter and fill. This is the way Honda makes sure it is cleaned out.

That’s a riot!

Why not just connect a tranny fluid exchange machine and get it over with?


I’m assuming OP doesn’t want to pay a shop to flush the transmission

I’m assuming OP wants to correct this mistake cheaply, and do it himself

I suspect db is right, and on that basis I agree with knifenmore’s advice.


Let’s look at the economics.

Tranny fluid on average is $6.00/qt

Depending on the tranny it’ll take 5-7 quarts to refill after a pan drop.

That’s about $36.00.

You do this 4-5 times you’re looking at about $150.00 just in tranny fluid.

And you still don’t know if all the gear oil was removed.

This doesn’t include the cost of a new pan gasket each time if it has one.

Then there’s the disposal of the used tranny fluid.

And then there’s the down time of the vehicle.

For about the same amount of money, you hook a fluid exchange machine up, get it done in one step, and you know all the gear oil has been removed.


The cheapest and best solution . . . in my opinion

Use another car to head to the parts store

Buy the correct quantity of atf and a filter and gasket kit

Head back home

Put the truck on jackstands

Do not start the truck

Remove the transmission pan

Clean the pan very well

Replace the filter

Clean off all remnants of the old pan gasket

Reinstall the pan, with a new gasket

Add the correct amount of the correct atf

Drive the truck for a few miles to get the fluid hot

Check the fluid level again, correct as needed


Why would you assume that? I asked for advice on how to get it done. And I’m very grateful to those who offered it.


The OP started the engine.

That means the torque converter operated the pump within the transmission and pumped the gear lube throughout the transmission.


So the only solution in your opinion based on the fact that I started the engine is a fluid exchange machine? Any comments on the use of a transmission flush product?

I don’t like transmission fluid exchange machines but it is the only way to go here.

You don’t need a transmission flush product.

All you need to do is have a transmission fluid exchange machine connected at the radiator at one of the transmission cooling lines. Fill the machine with the proper amount of transmission fluid, start the engine, and let the pump within the transmission push the contaminated fluid out while the exchanger pumps the new fluid in.

How simple is that?


Simple enough! I will have it towed to our local transmission repair. Thanks for the advice.

We make assumptions all the time

All of us on this forum, no exceptions

And I’m the villain, this time . . . ?!

Fine . . . I’ll take one “for the team”


But I’m not admitting guilt, fault, or anything else for that matter

I’ll just let you guys . . . and OP, if he chooses to do so . . . to label me as “the villain” this one time

Vehicle manufactures have recommended the use of a transmission fluid exchange (flush) machine in bulletins in the event of contamination, usually coolant or water intrusion.

However, many non-mechanics fear these machines and procedures, something could go wrong. Personally I have never witnessed damage from a fluid exchange and can’t imagine how it could occur. Just be sure you take your vehicle to a place with mature, experienced techs.

Is everybody happy now . . . ?!


All good!!! I’m the bonehead here. I’m new to this team and I’m glad I’m here. I like the heart. Thank you all.

The back story is that this transmission wouldn’t drive in any of the forword gears, only reverse. And it had no fluid. Through a confluence of circumstances I put the oil in. It’s my problem but not my truck. That’s the riot. All comments of all sorts welcome!