66rfe to bypass or not to bypass

[17Ramguy78]

I read that transmissions optimal temp is 170⁰ ish. That temp keeps moisture from building up I'm the fluid. I just got my truck a few months ago so no blazing temps. The temps were around 175 consistently now I put a bypass in it and it barely sees 120, have not towed anything nor seen hot weather in any case. I plan to keep the fluid serviced, should I be worried of over cooling my tranny, in Delaware we can get into some low temps but that is rare. I saved the oem thermo valve should I reinstall to keep my tranny at around 170?

 

[White six four]

I've never heard of a transmission failing due to being too cool, but I've heard of a lot of them that have "burnt up". Having a gm vehicle now I learned that there 6 speed transmissions had 190 degree thermostats. Gm even put out a tsb that they would replace it free of charge for a 145 degree tstat. So I don't think 170 is the "optimal temp" but that all varies depending on what you read or who you ask.

If you're worried about it I think mishimoto makes around 140 degree one for our trucks if I remember correctly. I put in a revmax a few months ago and have yet to see over 118 this winter. Shifts great especially with redline c+ so I'm not worried about the cooler temps.

 

[bigdodge]

The main cause for the thermostat to fail is from debris. Like what you see in the bottom of the oil pan. I have 131k on mine but have changed the fluid every 30k and never had an issue.