Synthetic differential oil

markss327 · Post by **markss327** » Wed May 21, 2008 10:59 am

Just curious of what ya'll think about synthetic differential oil?
If you've ever turned a pinion by hand, and I'm sure we all have, there is some serious resistance there. I'm betting synthetic will reduce the resistance, and the overall end result will be better 1/4 mile times. It seems like it would run $20 to $30 to fill a 10 or 12bolt.

Anybody currently running synthetic in their diff?

TheRookie · Post by **TheRookie** » Wed May 21, 2008 12:34 pm

When I had the BMW, oddly enough, there was one of the top BMW diff builders in the world right off 87 in Newbury. They only use synthetic in their race diffs. Royal Purple I think was the brand.

Basement Paul · Post by **Basement Paul** » Wed May 21, 2008 8:42 pm

I have synthetic in the S-10, the Trans Am, and the Cadillac... and when / if I switch the rearend into the T-bird, I will run it in that too.

Somewhere I remember an OLD test on synthetic fluids in a Mustang GT that showed the gains from the engine to the differential. I think the rearend was something like 2hp at the rear wheels, and in total from the motor, trans, and rearend was around 8hp, but it was a stick shift car. I think they used either Mobil 1 or Royal Purple (can't remember).

-BP