What is my Automatic Transmission operating temperature?
A question that gets asked the alot is what is the best temperature my automatic transmission should operate at? Most late model vehicles operate at 90°C - 95°C which is quite normal and what the transmission control module will operate its smoothest shift strategy. Now add our unique Australian climate and all your vehicle accessories then your GVM upgrades to allow that luxury touring van to be towed. Now where is our automatic transmission temperature operating at? there is also a head wind and a nice long incline and your asking yourself i wonder what my temps are sitting at now?
Put simply if you googled “My transmission failed due to running to cold“ how many results would show up? I searched this and the only results where relayed to manual truck gearboxes that mainly operated in freezing temperatures and failures where due to being frozen. That aside late model vehicles do use shift strategies to adjust and monitor temps but what happens when temp get to high?
Below operating temperature shift strategy.
When an automatic transmission is cold the Transmission Control Module (TCM) firms the shift strategy to work the fluid harder to increase temperatures.
Operating temperature shift strategy.
The best shift feel which is maintained by the TCM focused on occupant comfort and fuel economy
Above operating temperature shift strategy.
The TCM will attempt to decrease engine torque, lower shift pressures and apply higher gears to decrease engine RPM.
The next problem is if you monitor your temps using a Engine Guard or Scan Gauge the Automatic Transmission Fluid (ATF) holds its heat due to the higher flashing point as compared to your engine coolant. This means your on the side of the road waiting for your vehicle to cool down for 1/2 hour - 1 hour which may only drop possibly 10°C ATF temp.
Do i fit an aftermarket external automatic transmission cooler?
I would first ask are you monitoring you automatic transmissions temperature? if you are and it is constantly around 100°C or more then i highly recommend fitting one. If you do not have a device monitoring your transmission temperature i would first invest in a monitoring device.
Will an aftermarket transmission cooler void my new car manufactures warranty?
In past experience it comes down to your local dealerships Service Manage and Advisors who make the call. We have sold cooler kits to dealerships who then fit them to vehicles under new car warranty and they where OK with it. Most people who fit a cooler during warranty period will have other accessories and modifications to the vehicle the dealer would worry about. In the worst case a dealership is trying to use the cooler to get out of a repair due to a failure. The issue is most likely a common and a few screen shots of the issue from facebook groups etc will set them straight. But who knows an aftermarket automatic transmission cooler could have prevented the failure in the first place.
The conclusion to the temperature debate.
The cooler the transmission the best shift strategy for heavy loads due to increased pressure on shifting and no reduction on engine torque. Lower operating temps mean longer lasting fluid and internal components increasing your transmissions life expectancy.
See Also…
Monitoring your Transmission Temperature
Fitting an External Automatic Transmission cooler
Servicing you Automatic Transmission