Another CVT fluid question

[inuvik]

Just thinking out loud here. We all know that heat kills these CVT's with temperatures above 90C / 194F. Since the Mirage stock thermostat temp is 192F or 88C and the transmission is cooled by the a heat exchanger with the engine coolant it's a pretty reasonable assumption that our little cars CVT fluid temp spend a lot of time above 90C / 194F which reflects in the CVT fluid degradation values shown in the previous post. Which made me think why haven't we all put 180F / 82C coolant thermostats in so the CVT fluid never gets hot enough to degrade? Just wanted to put it out there before the thought left my leaky brain lol.

Motorad 2040192 is the OEM thermostat

Motorad 2040180 is the 180F thermostat

[thx1138guy]

That is an excellent idea. My 2014 Nissan Altima uses a 180°F thermostat. The CVTz50 shows that the CVT fluid temperature is always less than the engine coolant temp in my Altima which stays between 180 - 190°F year round. Except in a traffic jam on a hot day when the radiator cooling fan is woefully inadequate to maintain that temp range.

Anyone knowledgeable as to why there's a difference between manufacturers regarding choice of thermostat temperature?

[inuvik]

That is an excellent idea. My 2014 Nissan Altima uses a 180°F thermostat. The CVTz50 shows that the CVT fluid temperature is always less than the engine coolant temp in my Altima which stays between 180 - 190°F year round. Except in a traffic jam on a hot day when the radiator cooling fan is woefully inadequate to maintain that temp range.

Anyone knowledgeable as to why there's a difference between manufacturers regarding choice of thermostat temperature?

Emissions would be my best guess. But for comparison my 2019 Outlander Sport has a OEM 180F thermostat with the 2.0 4 cylinder.

[Top_Fuel]

...the CVT fluid temperature is always less than the engine coolant temp in my Altima which stays between 180 - 190°F year round.

I've always wondered about the operating temperature range of CVT fluid.

If normal CVT fluid temps are expected to be close to engine coolant temperatures, then why is the CVT overheating warning set at such a high temperature threshold in a Mirage? You will not get a CVT overheating warning until the fluid has reached 137C/279F. Maybe this is typical for a CVT?

This is from the Mirage service manual...

[Eggman]

I've always wondered about the operating temperature range of CVT fluid.

If normal CVT fluid temps are expected to be close to engine coolant temperatures, then why is the CVT overheating warning set at such a high temperature threshold in a Mirage? You will not get a CVT overheating warning until the fluid has reached 137C/279F. Maybe this is typical for a CVT?

Good point. Isn't the engine overtemperature warning lower?

Changing the thermostat only alters when coolant begins to circulate through the radiator on warmup. Does the radiator coolant circuit also serve the CVT? Or is it a separate circuit similar to the heater core and throttle body?

Besides, changing the thermostat doesn't change the amount of heat generated and doesn't change the capacity to remove that heat.