Changing rear diff oil

[Brutus]

Hopin to change my rear diff oil and transfer case oil in my '98 friday. According to my manual, it says I need to use a Hypoid Gear Oil API GL-5 in 80W-90. Is Royal Purple a hypoid safe oil? Plus I had trouble finding 80W-90, can I use something close like 75W-90?
If I can't find Royal Purple in my area, would Mobil 1 be sufficient and is it hypoid safe?

Thanks folks,

Brutus

 

[Stick Figure]

I would think you would be fine w/ the Royal Purple, i've never heard of anyone having problems w/ it in anything else of similar design.

I personally just ran redline lightweight shockproof. I have been using this in transmissions and diffs for a long time w/ great success.

 

[shootmymime]

i cant crack my fill plug loose! good thing i didnt drain it 1st!

 

[Elton H]

75w90 will work fine

 

[pat161]

Mobil 1 75/90 will work perfectly, I run that in both diffs and the xfer case, and even ran it in the tranny when I had my 00 5 speed.

As for the plug not coming out, they can be a pain as they sit for a long time. Try spraying it with some kind of penetrant a few times before going at it, I like PB Blaster but there are others. When you go to remove it instead of steady pressure on the wrench try hitting it to kind of simulate an impact wrench. I had trouble with the front plug, but a few taps and it broke loose.

 

[410toy]

I changed all my fluids over to Royal purple. Not one problem 10000 + miles it is the best stuff out there

 

[twitchee2]

i cant crack my fill plug loose! good thing i didnt drain it 1st!

Jack handles work wonders here. Mine had such a load crack when it finally broke loose ~3ft cheater bar


oh and im running royal purple 75w90 in front xfer and rear aswell.

 

[shootmymime]

i tried the 300lb impact but it striped part of the nut, so i gave u

 

[Elton H]

u think the rear is hard try getting that dang front diff plug off i pretty much destroyed mine

 

[twitchee2]

i tried the 300lb impact but it striped part of the nut, so i gave u

i tried my 650ft lb impact and that didnt break it loose. Granted it is from harbor frieght so its probly not anywhere close to 650ft lbs haha. Put some PB blaster r liquid wrench and get a big arse cheater bar. it will go.


My front was covered it grease. it came off just fine. just need a 10mm hex

 

[Brutus]

Mine came off relatively easy. My biggest problem was not havin a 24mm socket. Lucky I work close to home and went there and got it.
Couldn't justify $15.99 a qt for the Royal Purple so I went with Mobil 1 synthetic.

 

[Stick Figure]

i tried my 650ft lb impact and that didnt break it loose. Granted it is from harbor frieght so its probly not anywhere close to 650ft lbs haha. Put some PB blaster r liquid wrench and get a big arse cheater bar. it will go.


My front was covered it grease. it came off just fine. just need a 10mm hex

make sure you have the proper size air line to feed that gun, and i bet it is actually pretty power full. I picked up one of the BIG guns from harbor, and it was really pathetic until i ran the 1/2" air line to it, then it woke right up!

as for the diff plugs, all of my plugs came right out w/ a matco breaker bar. Probably a 36" IIRC.