Rebuilt 6l80 w/Mishimoto trans cooler

[Anthonyvee90]

Just installed a mishimoto trans cooler in a fresh rebuilt transmission.

The question I have is how to I read the dip stick now 

I waited until the transmission got to 130° and check the fluid while it was running on park. Filled it until it was in the hot section on the dipstick 

Did I do it correct or do I need to remove some 

thanks in advance 

[Grumpy Bear]

Your hot temperature is whatever your normal hot temp is, not a target in a book. That number is the value for a system with known ranges modulated by a thermal bypass valve. In my 2015 the hot read was done when it was over 192F to insure the TBV was open and the cooler full. When I added the 70 C TBV it never got that hot. About 175 is tops on a hot day now with the lower water thermostat. When adding a huge cooler I have to ask if a TBV is in play if so what the fully open temperature is. If not then I'd fill to the cold line following the book procedure of working the valve body to purge air and go with the cold reading. I doubt given the size of the cooler that if there isn't a TBV it will ever get hot enough to puke the breather or foam. 

Edited July 20, 2025 by Grumpy Bear