Hi,

I'm going to change the rear diff this weekend. Wanting to know which fluid ya'll recommend. Will any friction additive work. I don't think I want synthetic.
How many quarts should I buy? What do you recommend?

Thanks!

 

If you tow at all, go sythetic. If you have limited slip, get the Royap Purple 85w-140.
If you do not tow, the Valvoline 80w-90 is available in a blend for about $7/quart. I think it is about 4 quarts.

 

Syn 85-140 of choice and 2 bottles of LS additive.

 

Royal Purple has their rear dif fluid they recommend on their web site. Cant remember what it is but thats what I have in mine.

And yea I believe its 4 qts.

 

don't forget the correct fluid level is 1/2" BELOW the inspection plug. Don't fill it until it runs out. good way to lose pinion seals.

 

that's funny, i fill mine 'til it runs out and after 218000 miles no leaks

 

for the price and protection why not go synthetic. not to much more I have used royal purple and redline both synthetic and both have LS additive already in oil. after you change if its been a long time. some people like to lift up one side at a time and let gravity take its course to drain out what ever they can. scoop out all the nasty crap as much as you can. before I replaced my diff cover with aftermarket one. I got big magnets and stuck them on the cover to trap crap they worked great. after filling go and do figure 8's both directions to get oil seated in the clutches. I have never had to put more LS additive while using this oil. redline I can usually find alittle cheaper than royal purple. but I like both.

 

I did a pinion seal the other day. Last year did wheel bearings and used the Mopar 75-140 synthetic. This year saved a whopping $2 per quart and picked up some Mobil One 75-140 full synthetic. It was sitting right next to the royal purple that was a buck or two higher.

As far as I knew you had to run the synthetic in these diffs because of the LS. And why not, it only costs about $80 for the oil alone.......

 

Thanks guys! I used the royal purple 85w-140. And put the additive.
But I have a bigger problem. There where large chunks of something all over the place. Magnet was full of shavings. I think it might be the pinion bearing.
I need the truck for work so, just cleaned and flushed it best I could, and put the new stuff in. I drove it and it's alot quieter. I have an appointment with a shop on wednesday. Hopefully it will be ok till then.I just have to drive it. I think I have probably been driving it like that for quite some time.

I had the u-joints replaced a couple months ago, and the mechanic said there was alot of play in the pinion/driveshaft.