ok, thats good to hear....but i have one more question....then we can kill this thread lol. im running 80w-90 in the diff now. i went to the dealer and they had two different types of friction modifiers. one was synthetic and one was not. so i got the one that wasnt synthetic. simply because i know that in the manual for the 03's (which the salesman gave me when i bought the 01 cause mine didnt have a manual) it says that the rear diff takes 80w-90 for all applications EXCEPT the FX4. the FX4 takes 75w-145 synthetic so im assuming thats what the synthetic modifier was for. the guy at ford was no help lol. so i figured, if i went to autozone and had them pull it up on the computer, i was curious to see what it would say. it called for the 75w-145 synthetic..?
ok, so im lost. ive got the ford anti friction modifier that is not synthetic, the truck currently has 80w-90 gear oil in it. should i just add the modifier and be done with it? or should i dump the 80w-90 and put in the synthetic stuff like the all mighty autozone computer says? i trust you guys over just about everyone, so im looking for a little more feedback. the guy at ford did tell me that if he could read the tag on the diff, he could tell me what it got.......yea about that tag. remember i put a chrome diff cover on?......yea well the tag is.....somewhere in the garage.....hard to say exactly where. its dark and i cant see to be able to do a proper "scavenger hunt" for the tag. i know i kept it.....i think. anyways, this is the last post guys. sorry for the length. go get a beer before you answer, you've earned it