Royal Purple almost ruined my 9.75 rear

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Need4racin

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Around 130k changed original factory fill oil in the rear differential on a 2005 ford 9.75 rear. Ring/pinion and spider gears were perfect looking. Filled with 75w140 RP gear oil and motorcraft limited slip additive. 15k miles later passenger outer bearing/seal is leaking and causing the pass ebrakes shoes to smoke on highway. Opened up the differential now everything is covered in gray sludge, oil still light brown and clean, and ring and pinion has wear marks and spider gears have knicks all over them. Axles shaft wear surfaces still all looked good. Few metal specks on bottom of sump when I wiped it out. Now 3-5k miles on motorcraft synthetic 75w140 and motorcraft limited slip additive the rear axle is humming at 40+ mph. Did the royal purple gear oil have a bad reaction with the XL3 motorcraft LS additive?

I saved the old RP gear oil, guess I should send off a sample to have tested. Ive never had any problems with any oils; but i suspect this RP caused it. Gear oil was from AAP and got a good deal on it with coupon codes and LS additive was from ebay or amazon (maybe counterfeit copy?) trying to think of any possibilities. Any ideas?
 
I think there is more to the story than just RP ruined something. Was the anti-slip the proper stuff and proper amount? I would get a UOA done. Could you have gotten dirt in during the fluid exchange process? Seals leaking allowing water in.
 
Ive heard this before, Even though we are a RP dealer here at the speed shop here,I BEG and plead for customers not to buy it. just like the Lucas snake-oil stuff stay away from and buy standard brand stuff like you have known and trust.
 
Possible, maybe even likely that a bearing failed and that's the root cause of the grey paste, the nicks and so on. 130k on the factory fill and you're looking to blame RP? Too many unknowns for that. I think it would be prudent to tear it down and find out where the metal came from.
 
RP is not liked on this site, I'm sure you will get plenty of responses to support your theory!

I have ran RP Max Gear in my truck in the past without issue towing some really heavy loads, Same with Amsoil SVG & Mobil 1.

If the same would have happened with Amsoil SVG or god forbid a Valvoline product......People would say this failure would have happened anyway.

You probably have a Bearing going south on you & the damage was already done before the lubricant change.
 
Are there any other RP products to worry about ?
I use the HPM in my boat - and my boss swears by their Synchromesh in his manual transfer case ...
 
Not taking a side here but isn't (aren't) RP products made from Mobil1 basestocks?

Also, I think I've heard that Chrysler rears like conventional lubes (no?) so maybe it's a case of that in a Ford.

And as we all know, Ford NEVER makes any shoddy stuff or takes short-cuts. Kira
 
I seriously doubt that the rp oil caused the rear end to burn up. More likely that the 135k on oe fluid allowed some bearing wear and it finally gave up.

Rp may be over priced but I don't think it's a bad oil
 
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135k is nothing on a rear end.

RP is the problem.

I put this same oil into a Ford Ranger 5 speed transmission. It shifted much better during the winter. Now when I drained it(engine blew up) it literally came out like solvent!!! Thinner than water. It had SHEARED DOWN.

I was not happy. The whole point of using RP was for better fuel economy and winter performance, I had NO IDEAL how it sheared so quick. I only had 30k on the oil when I drained it.

I thought synthetic was more resistant to shearing, Royal Purple is a disappointment.
 
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I had Shell 75w140 water out and ruin a Dodge 1500 rear in just 30k ...

Nothing but Delvac Synthetic for me ...
 
Originally Posted By: Vern_in_IL
135k is nothing on a rear end.

RP is the problem.

I put this same oil into a Ford Ranger 5 speed transmission. It shifted much better during the winter. Now when I drained it(engine blew up) it literally came out like solvent!!! Thinner than water. It had SHEARED DOWN.

I was not happy. The whole point of using RP was for better fuel economy and winter performance, I had NO IDEAL how it sheared so quick. I only had 30k on the oil when I drained it.

I thought synthetic was more resistant to shearing, Royal Purple is a disappointment.



You used a 75W140 differential lube in a Manual Transmission?
 
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Originally Posted By: clinebarger
RP is not liked on this site, I'm sure you will get plenty of responses to support your theory!

I have ran RP Max Gear in my truck in the past without issue towing some really heavy loads, Same with Amsoil SVG & Mobil 1.

If the same would have happened with Amsoil SVG or god forbid a Valvoline product......People would say this failure would have happened anyway.

You probably have a Bearing going south on you & the damage was already done before the lubricant change.


Originally Posted By: The Eric
Possible, maybe even likely that a bearing failed and that's the root cause of the grey paste, the nicks and so on. 130k on the factory fill and you're looking to blame RP? Too many unknowns for that. I think it would be prudent to tear it down and find out where the metal came from.


I doubt the Maxgear caused any problems.

What I think happened was the Maxgear cleaned out a worn and false axle seal due to sludging and your seal was already on it's way out.
 
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Originally Posted By: Donald
Amsoil SVG gear oil.
+1 - but did you save a sample of the factory fill? Was it also gray? I am not an RP user, but it would seem strange that it caused a failure in 15K miles.
 
Originally Posted By: bullwinkle
Also, RP gear oil doesn't need LS additive-according to them, it has LS additive built in.
http://www.royalpurpleconsumer.com/products/max-gear/

The Ford Limited Slip is very picky when it comes to friction modifiers, regardless of fluid used that has LS additive (RP, Mobile, Valvoline, Lucas, WalMart etc). There are too many real world complaints of using fluid that has a LS additive in it and the Ford LS still having chatter until LS additive (preferably the Ford XL-3) is added.
 
I personally ran RP in my Subaru from 1,800 miles up to ~32K. When I drained it after a 30K interval, the fluid came out as an opaque silver-grey color and appeared very viscous. I put in Amsoil SVG and ran that for 70K miles and it came out looking like a new fluid -amber colored and translucent. I know that looks aren't everything but I was really impressed with how much better the Amsoil looked after 2x the interval. I personally will not be running RP again in my diffs.
 
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