Transmission Fluid Temp. - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

RBR · 09-03-2012, 18:52

I am driving a 1999 Taurus Wgn with a 3.0L. I recently purchased a 10 ft. pop up trailer which I have pulled to a couple of camp sites both within 75 miles from home. The land is pretty much flat and I won't go much further. I am trying to determine if it is necessary to install a cooler. I know that normal temp's without anything on behind with the A/C on are: ECT=198 F & TFT=205 F as I bench marked them with NGS. Travelling the same speed, but with the trailer on behind and a warmer day (87 F) Temp's were ECT=200 F & TFT=207 F. Then I turned on the A/C and the Temp's were ECT=214 F & TFT=220 F. As long as I kept the A/C off the 2 temp's towing the trailer without the A/C on were exactly the same as driving with the A/C on without the trailer on behind. As long as I tow without the A/C on I'm pretty sure I'm OK, but on a hot day the A/C sure felt good! I was regulating the Trans Fluid temp by turning the A/C on and off! At what temp. does the transmission fluid have to be, before damage starts to occur?

**Bert** · 09-03-2012, 19:10

ATF Temp Chart This is the same for any transmission.

**360ci** · 09-12-2012, 21:30

When towing with any vehicle, it's best to lock out OverDrive and stay in a 1:1 gear or lower. This will aid in cooling all around and engines are built to RUN. If you have the 2V 3.0, it won't have any problems running at 3500rpm on the highway - I know.

Heat is the enemy of any transmission, higher temps over time will break the transmission fluid down quicker. Once the fluid heats up, the internal transmission components heat up even more and the transmission fluid becomes useless and you risk burning things out.

I tow a LOT with my Durango R/T, and with multiple coolers (for almost every fluid), I change my transmission fluid every 30K like clockwork although temps never exceed 200F, even when towing three tons up hill - in 3rd gear (1:1). I don't exceed 68mph when towing.

The mileage deficit isn't very much when towing in a lower gear to keep the engine in the mid-range (or torque band). Again, it will also help lower temps by providing more fluid flow to vital transmission components. Lugging the engine (say, overdrive into a headwind) can cause a lot more harm then using a lower gear to prevent this.