I have an 07 5.9 liter 2500 4x4 and I need to change the gear oil in both diffs. I have valvoline synthetic 75w140 would that product be ok to use and also what is the fluid levels for each differential I have had it done at the shop previous times but moved and don't trust a soul around here with my baby please help! Oh yeah and I don't know which rear end I have help on that would also be greatly appreciated!

 

yeah that fluid will be fine, the level your going for is about 1/4 of an inch below the fill plug, 8 quarts should do it (you could always return it if you don't use it all) and if your not doin it on a lift you might need to take off the LF wheel and disconnect the tie rod to get the cover completely off. Not positive though. You do have the 9 1/4 up front and 11 1/2 in back right? For future reference if you do have these axles the right fluid is syn 75 90 weight, 140 is a little overkill unless you tow heavy...

 

I tow a 16000 pound 5 th wheel, not very often but I travel and work but thanks the information is greatly appreciated!

 

Yeah, a synthetic 75W90 rated GL-5 is what the book calls for.

On the rear end of some trucks (might have changed) there is "Fill Line___" stamped on the rear cover. The fill line is about 3/4" below the bottom of the hole.

Also the book says 24 ft lbs fill plug and 30 ft lbs cover bolts. There have been quite a few threads about broken cover bolts, so I wouldn't tighten them quite that much. On my 03 I did the first change at 30 ft lbs with no problems, so I thought maybe some had weak bolts and mine were fine, then the head twisted off one on the next change. It was hardly snug when it snapped.