8L90 Transmission Operating Temperature

[TruckinCountry]

I have a 2016 Chevrolet Silverado V8 5.3 pickup with the 8L90 transmission. What operating temperature should I be running? Just looking for feedback on standard operating temperature for daily driving with no load. Any feedback regarding transmission operating temperature is greatly appreciated. Would like to hear from some who run the 8L90 as well.

 

Background: I got a transmission shop trying to tell me that 120*F and under is normal operating temperature for a transmission with the bypass valve. Not buying it, so just gathering some information to back me up to provide when I pay them another visit. Feel free to provide your feedback on that claim as well.

Edited March 23, 2023 by TruckinCountry
Add fahrenheit, fix spelling

[rav3]

Interesting question. Check out this updated TSB from GM about changing the transmission thermostat from 90C (194f) to 70C (158f). with that said, what is normal?

The old 4 speed transmission didn't have a transmission thermostat at all. to get more MPG, GM decided to heat up the transmission fluid to make the fluid thinner. So they added a 90c thermostat on your transmission. Then the transmissions/torque converters started failing, so now the have a TB to install a lower 70c thermostat. 

Most experts will tell you that the worst thing to kill a transmission is HEAT. I did the "pill flip" on my 6L90 & mine runs between 115 to 150, depending on ambient temps, even driving in our mountains in WNC. 

In my opinion, what you guy told you is pretty correct, when not towing or hot rodding.

If I were you, I'd do the pill flip or there's a kit out there to modify the thermostat to stay open & fluid will run just like all the earlier truck transmission.

Hope this helps

 

21-NA-199 1..3 (nhtsa.gov)

[newdude]

2 hours ago, rav3 said:

Interesting question. Check out this updated TSB from GM about changing the transmission thermostat from 90C (194f) to 70C (158f). with that said, what is normal?

The old 4 speed transmission didn't have a transmission thermostat at all. to get more MPG, GM decided to heat up the transmission fluid to make the fluid thinner. So they added a 90c thermostat on your transmission. Then the transmissions/torque converters started failing, so now the have a TB to install a lower 70c thermostat. 

Most experts will tell you that the worst thing to kill a transmission is HEAT. I did the "pill flip" on my 6L90 & mine runs between 115 to 150, depending on ambient temps, even driving in our mountains in WNC. 

In my opinion, what you guy told you is pretty correct, when not towing or hot rodding.

If I were you, I'd do the pill flip or there's a kit out there to modify the thermostat to stay open & fluid will run just like all the earlier truck transmission.

Hope this helps

 

21-NA-199 1..3 (nhtsa.gov)

 

 

This is for 6 speed, not 8 speed.  

[newdude]

2 hours ago, TruckinCountry said:

I have a 2016 Chevrolet Silverado V8 5.3 pickup with the 8L90 transmission. What operating temperature should I be running? Just looking for feedback on standard operating temperature for daily driving with no load. Any feedback regarding transmission operating temperature is greatly appreciated. Would like to hear from some who run the 8L90 as well.

 

Background: I got a transmission shop trying to tell me that 120* and under is normal operating temperature for a transmission with the bypass valve. Not buying it, so just gathering some information to back me up to provide when I pay them another visit. Fell free to provide your feedback on that claim as well.

 

 

8L90 on 15-18 trucks the stock TBV is full open at 194F. 

 

If the pill has been flipped or the SureCool aftermarket TBV bypass was installed, you'd see 100-130F.  

Edited March 23, 2023 by newdude