Naw... I used the RP in my 2002 RAM's Power Steering pump...

I still have the stock fluid in the 06.

 

IMO, the DC 75w90 is barely good enough for a grocery getter! I put the first 9k miles on my 97 with that stuff and it looked like road tar and smelled even worse and that was only towing 7k lbs. I bought my 03 with 25k miles and it was obviously used to tow heavy - 5er hitch boltholes, airbags and paint worn off of the OL spring ends. I think the first owner ran the OEM junk too long cuz I checked the pinion and carrier brg preloads and they were already down to <1/2 of the the used brg. rolling tq. specs. I think they need a minimum of 75w140 for any hauling. That's what I use now but I'm going to 85w140 next time. I've seen that stuff hold up to heat on brgs til h@ll wouldn't have it! When I change diff lube, I also parked it pointing downhill, hold my thumb over the lower half of the fillhole and put in 5 qts. Nobody will ever convince me that the fill hole level, way below the axle tubes is high enough. My 97 had wheel seal problems til I put in an extra qt. and my 03 wheel brgs were all gunked up with old, burnt oil from the lack of fresh oil to them. BTW, RP makes syn PS fluid - I've run it for years. My 97 didn't have a PS cooler and would scorch the fluid badly, so I got into a habit of routinely changing it, too. Craig

 

what weight fluids should i put in my diffs down here in texas? i dont do alot of towing, i just want a good fluid and will take care of my diffs.

 

I really think a minimum of 75w140 is good for any normal conditions and especially if you do any towing/hauling. From my own experiences, I don't have any use for 75w90 anymore - it just didn't do the job in the rear of my 2wds. I ran the 85w140 in Co. winter and never even saw a downside then - it was all win win win (lower temp, less wear and better UOAs). No loss of mpg or too stiff when cold but my truck was garaged every night and I never needed to use it below 0. A whole bunch of guys have switched to 75w140 and really like it and I have yet to read about anyone who switched to 85w140 and had a complaint. From what I've read, the 85w140 guys have had similar problems as I've had with lighter weights. Craig

 

The rear end that I burned up had just been rebuilt, new bearing and gears. It had between 200-300 miles on it when I got on the highway, 50 miles into it I turned around and barely made it home. I was running empty at 60-65 mph.
I rebuilt the rear end again, this time I used Mobil 1 synthetic gear lube, it was still there when I sold the truck 60k later.
My friend's 1T had about 80k on it and he put in RP 85-140, he tows most of the time, usually 8000-10,000lbs. He made it about 600 miles, lost the gears and bearings.
Maybe they've improved the stuff since then, but I'm not trying it again.

 

I have had good luck so far with Mobil 1 75w90. Any GL-5 rated synthetic gear lube in 75w90 or 75w140 should work great.

I think it helps to have the extra capacity of the Mag Hytec Diff cover.

 

I use RP products in exterem conditions not just on my truck. I can tell you it sure wasn't the fluid. With a fresh rebuild I would be looking more to the installation then the fluid. But hey to each there own.

 

Can't we do a poll or soemthing? 1st gen tow no tow, 2nd gen tow no tow 3rd gen and local temps? I am doing mine pretty soon and would like to know the very best for my situation. 2001 quad 87,000 miles for towing toy hauler in the 40-115 degree weather(just incase the poll thing doesn't work)

 

I'm in the same boat - don't do any serious towing so I went with the Amsoil Severe Duty SVT 75W-110. A bit more protection than a 75W-90 but not the full on 75W-140. So far so good. I also added a PML rear cover at the same time, IIRC, with the PML, the rear end took almost 6 qts.

https://www.amsoil.com/storefront/svt.aspx?zo=1478251

 

I suspect with mine, being all new, something could have been in question. However, my buddy's 1t used the same oil out of the same 5 gallon pail. There was nothing wrong with his rear end before the service change and it took the same damage. My conclusion based on; same oil, same damage= crappy oil. When we sent the bearings out of both to R.P. their reply was "defective bearings, not our fault."
At the time, they made all kinds of claims about their super additive, not needing any kind of friction modifier, that was B.S. too. Both of our trucks had to add the friction modifier to quiet the chatter.
This has been a few years ago, we saw a booth at a product show and the guy selling it was pretty slick. Like I said, maybe they've improved since then, but I'm not buying it.

 

Make a list of all the big names and throw a dart! You could be a weather teller if you can figure out which one is the best! It's more important to find one that does the job for you. IMO, at least 75w140 for 115 ambient. As long as the lower # is 75w, its the same for the colder climate but the higher # is what's important for the hot climate. You need to do UOA (an excellent thing to do) to see how it holds up, chemically. My experience, as far as the best wear indicator has been - I believe what I see on the magnet (or better yet, what I don't see) cuz I've had UOAs lie about wear metal. The UOA can't show all the wear metal when it's stuck on the magnet! That's the only time UOAs have let me down. Craig