R5000si

The thermostat in the 6R80 trans makes the Oil reach 180 degrees then allows the Oil to circulate to the Oil cooler. I can see this would be nessasary if your located in snow country. In Southern California by the time the Oil heats up and just driving normally the Oil temp on my car is up to 200 to 210 degrees. That’s close to the temp that Oil breaks down which is around 240 degrees. What would be your opinion to eliminate the thermostat to allow the Oil to run cooler. This would also help the tranny to last longer. Would this be good or bad in some way that would damage the transmission. Thanks for your help!

Derf00

In the 05-2010 mustangs with a 5r55s they have the same type of thermostatic valve. Pretty much every aftermarket upgrade kit for the valve body locks the thermostatic valve in the open position or replaces it with a dummy valve to allow fluid flow at all temps for the same reasons you stated above, better lubrication at all temps, less breakdown of the fluid, longer tranny life.

I can't imagine why you would not be able to do this with the 6R80 tranny as well but I've never researched it. You may want to look for a shift kit from Sonnax, Transgo or Shift Technologies to see if their kits offer a Thermostatic valve lockout. ..


Hmm, I don't see it listed with Sonnax. You may have to go googling it to see if there's a manual way to stick it in the 'open' position, you can't simply remove it. It may affect the internal pressures.

https://www.sonnax.com/tech_resource...ve-body-layout

Hrm...your's seems to be outside the tranny?
Anyways, interesting read on it... May cause OBDII issues if you disable it.

http://www.gearsmagazine.com/resourc...2692778000.pdf

R5000si

Thanks Derf00 for your reply, it is exactly the information I needed and didn’t know how to find. The Gear Magazine says if the thermostat is removed the overdrive lockup will not take place if the Oil is not the right temp. If this happens can’t this be overridden with the paddle shifters on the steering wheel. So that 6th gear can be engaged with lower oil temp. About the the oil pressure drop the only way I could know if the pressure is to low is with a pressure gauge inline with one of the oil cooler lines.