Transmission Fluid Change

[redwoody]

Originally Posted by johns4dor

I tried to answer this sooner today, but my computer wouldn't let me on the site. I see from your post that you have obviously already done a lot to your truck. I notice you have the 203 stat. Is it from Dieselsite? Do you also use the Evans Waterless Coolant? On to the the trans now. NO, the little cooler behind the license plate isn't the trans cooler, it is for the Power Steering. The trans cooler is in front of the radiator, but I think on the diesel it is between the inter-cooler and radiator. A friend of mine who tows a 15,000lb 5th wheel toy hauler recently told me that he had a trans cooler from a 6.0which is supposed to be larger installed in his truck in place of the stock cooler. He also has the mag-hytec pan which gave him 24 qts before he added the 6.0 cooler. He says it runs 150-170 now. Huge drop according to him. I installed EVANS Coolant, and AMSOIL with a by-pass filter in the engine, and AMSOIL in the diffs for him but he hasn't changed the ATF yet. The dealer fixed his trans 3 times under warranty because of the big trailer and now he is just doing whatever until it blows. Guess he just wants to keep changing the ATF every 30,000 miles. It appears you are doing most everything to eliminate the heat. It mostly comes from the slip in the trans. You should stop some of it with the shift kit, that will raise the pressures and stop some of the trans slip and you already have the TQ lock-up. Do you have an aftermarket TQ? They will stop some heat too. A big pan helps by increasing the fluid capacity. And the biggest thing you are doing now is the AMSOIL. On average it will drop the temp by 10-30 degrees and I have heard claims of more. It also won't be affected by small spikes in temp like other fluids. Hope everything comes together for you.

I do have the 203 stat. it was mostly an experiment when I changed the coolant. I was hoping for an increase in mileage. my truck LOVES the heat. gets upwards of 20 to 22 when the temps are hot. and that is with the AC on and about 800 lbs in the bed and 3 guys in the cab and speeds under 65. I am using "stock" motorcraft green coolant, distilled water, and the motorcraft additive. should I go back to the stock 180 or 190 stat? seems to reason that the 203 will cause the engine to run hotter and the computer to activate the clutch fan more often to keep the motor cool??? this in turn, robs power and fuel economy during hot days??? am I correct? the guy I called at Dieselsite explained it differently. talked me into it.
I have been running Amsoil since the truck had 20,000 miles on it. good stuff. I know I don't want the trans to run too cool. you want to burn off any condensation for sure. I "use" the tranny but don't abuse it. I never mash the throttle especially when towing and I keep an eye on the temps. the TC is stock. thanks for all the help/thoughts and advice.