I use Mobil 1 fully synthetic in everything. Engine Oil, differential fluid you name it and it has never let me down.

 

Going to be doing changes soon, stumbled upon this on the net, seems like a good set of legit testing,

I was leaning towards Royal Purple... now it looks like Amsoil, Mobil, or Castrol for me.

http://www.synthetic-oil-tech.com/Ge...te%20Paper.pdf

 

Royal Purple makes a great product. We use Royal Purple in all of the race engines on methanol. I don't have any experience with their gear oil, but I would imagine that it is nothing but great. I'm almost certain that HPTV did a chassis dyno test with a gear oil change in the rear end and picked up like 4whp or something.

 

I have seen their motor oils, hence why i was considering their Diff oils. However, the results on those tests (especially the shear, cold viscosity, and the oxidation tests) kind of push me away from them.

I never do tons of hauling so I am sure I could look at some others that preformed well under everything minus the high load areas.

Surley all of them are still good gear oils. just trying to find "the best" is different to each person.