idea-catalyst

I really don't want to step into it at this point, but I do have one question. If the use of the RP and the reassembly of the diff occurred at the same time, is it possible that the diff was not set up properly? If the gears were not properly adjusted, could there have been a problem even with good oil? If the diff reassembly and the oil change happened at the same time, it might be difficult to separate the cause of the failure. Just asking.

H22toF20

I run Royal Purple in my motor, tranny and diff. No problems at all. Plan on changing everything here soon. Gonna make it a yearly ritual.

slipstream444

You would have needed to read the previous posts to get the full picture. The diff in question was the rear axle of a 1999 Jeep Grand Cherokee. The diff wasn't disassembled - No part of the differential assembly in the center (pumpkin) was touched - the right axle shaft was removed to inspect the outboard taper seat bearing at the end of the axle, due to noise at the right rear. There is no "setup" involved. The shaft goes in the same way it came out - no adjustment was made or required. The bearing in question was revealed to be in perfect shape prior to the installation of RP. The noise was due to the parking break being out of adjustment. The only variable that accounts for the near immediate destruction of all of the bearings was the fluid - which was switched to RP. The Dana rep that tore down the rear end said the rear end was assembled correctly (I can assure you I asked - to ensure there was nothing the dealership could have done to cause the problem - and he had no reason not to give me the facts), and the failure was due to the fluid. He specifically asked me what was in the differential - and I told him it was Royal Purple. He said he had seen a number of rear ends come into their shop with problems that were running RP.

I think I would have been more forgiving if the circumstances were tied to a bad batch of RP - and RP would have taken care of the problem. It seems this may have been part of the problem. However, based on the performance of RP outlined in the White Paper posted above, it seems at least a good part of the issue is their gear oil is pretty much a very substandard product on a good day, let alone accounting for batch variability and poor quality control.

H22 to F20: I post information to help others out. You are free to use it or ignore it. I don't like making claims unless I have a factual basis to do so. I don't make money by advocating Amsoil, or any other product.

The problem with oil is you won't know there's a problem until you have a problem. RP has proven to me they are 80% marketing and 20% product. They advocate non-standardized demonstrations (not valid tests) to sell their products (Timken "test" - BTW: brake cleaner produces the best results in the Timken test). If you like the pretty food coloring, and it makes you 'feel' special for spending your money on the product - keep using the product, after all, I don't have to pay your repair bills.
I personally use Amsoil ATM 10W30, MTF and Severe Gear 75W110. I know for a fact they are the best lubricating fluids for my S2000. When something better comes along - I'll investigate it thoroughly and begin using it when it proves consistent. I only have loyalty to products for as long as they work well.