I've got a 1994 F-150 with a 302. Got the 3.55 gears and trans cooler, also got super cooling. The truck has 92,000 miles on it. I ran Castrol 10w-30 gtx in for all I had it. I switched to syntec but due to the consumption i went back to gtx. I change every 2000 miles. I'm going to go back to a full synthectic but i debating whether or not to go with mobile1 or back to castrol syntec. also whant to know if you can drain the power steering system thoughrly.

 

After 92,000 miles of good service, why do you want to change now? I would just stay with the 10W-30 GTX, and extend your drain intervals. 2000 miles is overkill, unless you only drive that much in a year.

Jim

 

I'm with Jim, Castrol GTX is good oil so why abandon it this late in the vehicles life? I doubt you will experience much if any benefit in a vehicle with high miles using a syn.

 

I see you say you have a trans. oil cooler, did anybody put a temp gauge in the trans line to see what temp the trany runs at and how hot do you think is to hot? If the engine runs 185deg and the cooler lines run threw the radiator that means the trans must run hotter,to be cooled there.
I beleive that Mercon V ATF fluid is synthetic and can take the heat, but my 150 pulling my camper got up to 225deg on trans temp gauge for a half a hour whle chugging up a mountain in Wyoming. I plan a new deeper trans pan, but at this point does any one think I hurt it? Jim
2000 7700 5.4 w/Trailer package from Ford

 

Getting the ATF up to 225 could be a problem but depends on the type of fluid. If it was 100% synthetic you shouldn't have any problems. Non synthetics probably start to break down a bit at that temp but still provide protection. If you are towing you need to change out the fluid more frequently, and I would definitely switch to a synthetic ATF.