Help! There’s Transmission Fluid in My Coolant Tank

Reader Question:
Hey. Yesterday I was in a hurry to put some antifreeze or coolant into my car and accidentally grabbed the wrong bottle and poured two cups full of transmission fluid into my coolant tank. Will this harm my car?
What should I do? Matt


Sell this car QUICKLY! The damage can be huge and super expensive. Ok…..I was just kidding!
I have heard of people doing much worse. You really need to have your cooling system flushed
out real well though. I would take the car to your local quick lube place and have them flush out
your cooling system and install new coolant.

It would probably be a great idea to replace the thermostat too, just as a precautionary measure….
and preventative maintenance.

If you have not started the engine and you just poured the fluid in the plastic overflow tank….
DON’T START THE ENGINE, just remove the small rubber hose from the bottom of the coolant
tank (or just remove the tank if you can’t get to the hose) and flush and drain the tank of the fluid
with a water hose. There is no need to do anything else IF you have not started the engine.


Austin C. Davis

Posted in: Reader Questions

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