Hi, guys,
I'm looking for the axle gear oil for my truck. Does Mobile 1 fully synthetic (no LSD additive) 75W-90 work well? I believe my truck has the posi traction, which is not the LSD. So, no LSD additive is required. Also, does an inexpensive gasket under $10 work okay (the OEM one costs $30)? Any tip from you appreciated. Thanks.

 

What does the manufacturer recommend? Synthetic oils do work well! They are expensive though. The good thing about a front or rear differential is that those oils don’t need frequencies changing.

Why do you want synthetic? Do you tow often? How many miles on the truck? How sound is the rear end? If you are going to put synthetic in be sure to check & replace axle seals to avoid putting in replacing that synthetic before you need to.

 

Owner's manual lists a GM product number and doesn't tell if it's mineral or synthetic. The truck has 110k miles. I don't tow or haul anything heavy. The rear axle sounds as good as when the truck was new. So, it sounds like I don't even need synthetic oil. Do you have any product name in mind?

 

I don’t want to talk you out of synthetic but if there’s no real reason to use it then OEM recommended fluids work great. I buy comparable OEM fluids at Advance Auto, Pep Boys, etc.