I'm getting ready to have the rear end oil changed and want to know what type of lube to use? I am thinking either Mopar or Royal Puprle. I like the Royal Purple oil but have heard bad things about their transmission fluid so I don't know about the gear oil. What weight should I get? I'm kind of leaning towards the Mopar brand just because thats what comes in it from the factory so I'm thinking it must be one of the best. I can get a discount on the Mopar also through my work but then again price isn't really a big deal I just want the best. What do you guys use?

 

redline 75w90ns... or amsoil. only 2 worth considering.

 

Where can I get either of those? The only time I've used Amsoil stuff is in dirtbikes and I've never heard of Redline. Is the Royal Purple not good?

 

i have the royal purple in mine , i bought that stuff, because they said you dont have to add any diff additive to it, 75-90w at summit, maybe about 9 months old and no problems, hopefully its good stuff, spendy though

 

If I get Mopar fluid do you have to add anything to it or just pour it in? Same goes for the other fluids. Gear oil is what I want right?

 

It all depends on what type of differential you have. If it is an open diff, then yes, you just pour gear lube right in until it is full. If it is a limited slip differential, you will likely need a friction modifier, or else you will have chatter, and eventually destroy your limited slip. Some limited slip differentials can get by without friction modifier as long as you use a synthetic gear lube. However others (like my Auburn unit) specifically call for non-synthetic hypoid gear fluid, and Ford or GM friction modifier. I just depends if your limited slip is a gear driven, or clutch packs, or cone style. Cone and clutch usually require friction modifier.

My '99 1500 calls for 80w-90 in the front Dana 44, and 75w-90 in the rear corp 9.25. However, my rear limited slip also calls for 80-w90, so that is what I use all around now. You can tell if you have a limited slip by looking at the tag in your glovebox or on the door (can't remeber which place says it). But if you are not the original owner, you should make sure a previous owner didn't install one. Jack up the rear end just enough to free turn the tires. If turning one side in a forward direction causes the opposite tire to turn in a backward direction, you have an open differential. If both turn in a forward direction, you have a limited slip.

 

Would a 01 Ram 1500 Offroad Package have a LSD? I might have to go check in the door. What friction adder should I use if I need one?

 

If it's just a factory installed LSD, use whatever is called for by Chrysler, probably Mopar friction modifier.