Originally Posted by geg

I drew attention to your words "... and made certain to slightly overfill ...".
The pressure in the automatic transmission is quite serious, therefore, the excess of the transmission fluid level contributes to the squeezing out of rubber parts (gaskets, oil seals, sealing elements inside parts, etc.). If the automatic transmission is new, it successfully resists breakage; if the automatic transmission is worn and has the beginnings of future problems, the increased pressure hits the weak points and breaks the defense. I think that by exceeding the pressure and at the same time applying hard firmware, you unwittingly contributed to the death of some kind of automatic transmission organ. Professional diagnostics will reveal the place where Satan is hiding.



Where can the transmission fluid go? Either outward through the filter cover, or into the radiator through the cooling unit.

Originally Posted by Oldblue

Agreed, Geg, over filling can be detrimental to the internal seals of the automatic transmission, as can retuning the transmission shift points.
In this case , age of the parts can also cause problems, such as sticking solenoid valves.

Thanks to fastsuv there’s a how to thread

https://www.chevyhhr.net/forums/driv...olenoid-61313/

Originally Posted by fst100

I didn't overfill by alot. For example, if a drop the pan can fill 4.4qts, I filled it to 5qt even, but not like I poured 6qts. Also I had read it was better to slightly overfill to ensure the shift solenoid didn't get enough lube to overheat and fry which I read in some of the other past threads.

Originally Posted by tiapetra

This is priceless.