Royal Purple 75/w140 Synthetic:

Joined
Oct 13, 2014
Messages
114
Location
US
Had more build up on my drain plug for my transfer case using RP 75w90 then compared to the other gear oil thats been used in it. Not bashing them. Just felt for the cost I and my criteria the plug should have had less then the previous oil (mobil 1). Running Amsoil SVG. If you pick the Castrol please post a UOA and some pics of the drain plug.
 
Joined
Nov 8, 2003
Messages
3,863
Location
Cape Cod, MA
When I needed new axles and bearings in the wife's 2003 Mercury Marauder (not the one in my sig), the shop asked if I wanted the stock 80W-90 or RP 75W-140. I said RP and it's been in there for at least 3 years..in that time she's driven up and down the Atlantic seaboard, including a good run around Atlanta Motor Speedway at 110 MPH. Rear end is still smooth and quiet.
 
Joined
Jan 18, 2013
Messages
744
Location
usa
Originally Posted By: Ken2
Why is Royal Purple thought of as something especially good?
My guess because its likely from not many know about it, so it must be a better product. I was in that group before coming here. So I speak from experience. Just the facts from science.
 

MolaKule

Staff member
Joined
Jun 5, 2002
Messages
22,374
Location
Iowegia - USA
Originally Posted By: Ken2
Why is Royal Purple thought of as something especially good?
Price! About 150% above every other differential fluid.
 

01rangerxl

Site Donor 2021
Joined
Apr 8, 2006
Messages
10,528
Location
Birmingham, AL
I ran it for about 80K-85K miles in my truck's diff, but I used the 75W90 variety. No complaints. It only got changed because the pinion seal was getting replaced too. Draining the diff is not required for that job, but it seemed like a good time to go ahead and do it. The only reason I did not use it again was that I could not justify the price in a not very picky application. Used Valvoline SynPower 70W90 this time for almost half the price.
 

Doktor_Bert

Thread starter
Joined
Oct 21, 2014
Messages
120
Location
Palm Springs CA
Originally Posted By: 01rangerxl
I ran it for about 80K-85K miles in my truck's diff, but I used the 75W90 variety. No complaints. It only got changed because the pinion seal was getting replaced too. Draining the diff is not required for that job, but it seemed like a good time to go ahead and do it. The only reason I did not use it again was that I could not justify the price in a not very picky application. Used Valvoline SynPower 70W90 this time for almost half the price.
Thanks... We get it for free from a supplier, so I thought I would use it...
 
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