diff. fluid?? synth or std oil
 

Hey all,

I have a quick question, I am not rebuilding my rear end yet but am going to in the far future.
At this time I am replacing leaking rear cover gasket.
I am going to use synthetic without friction modifier. Anyone have an opinion either way??
Use std gear oil or Synthetic, all opinions welcomed.

John

Synthetic, it will also make clutches in posi units lock up quicker.

I would use standard oil for the first 300-500 miles after the rebuild, then change it and run synthetic.

I used Amsoil (synthetic) and one bottle of Ford Friction Modifier in my rear-end that I just finished up a few weeks ago. I upgraded my 8.8 with an Auburn Pro unit, Moser 31 spline C-clip axles, 3.73 ring and pinion, T/A performance girdle/cover with ARP stud kit.

No problems here.

Happy motoring.

E

I know with my Eaton, it said do NOT use synthetic. But mine is not a clutch type so I really dont know.

just returned
 

Hey everyone,

Thanks for the extra info, I just changed my oil and put synthetic back in. The speed shops I talked to said with synthetic I dont need modifier. I have a couple of hundred miles on it and it acts same as before.
When I rebuild I am not sure what setup I will go with stock rebuilt or other type posi unit but either way I know more about rear end fluids now.

Thanks,

John