What REAR differential do I have?

[joe90]

Going to change the fluid in my '99 hoe after 200k. Manual says 80W-90 and no friction modifiers for Locking Diff.
I bought Mobil 1 75W-90 LS synthetic based on a search but dont know if I have standard axle or not. How do I tell? I have GT4 in glove box but no G80.

 

[SunlitComet]

g80 or not, you need no modifiers and synthetic will do you just fine. btw you have an American Axle Manufacturing axles 8.5".

---------- Post added at 06:47 PM ---------- Previous post was at 06:42 PM ----------

btw i read in one of your other posts from january that you said you might have red fluid in your tcase? if this true get it out of there now. you are supposed to use autotrac2 fluid only. it is colored blue.

 

[joe90]

So I should not use the mobil1 ? What about the 75w 90? Dealer says use what the manual says 80w 90. So the gt4 is not ls? Why not use modifiers? How do you come to that conclusion? I already bought modifiers I have been waiting for 3 days now waiting to get this fluid in waiting for the right answers! So I have to take the mobil1 back and get what? The t case now has auto trac in it? Just waiting for this stupid rear diff. Thing to be over with. I don't know why advance autu parts recommended ls after they looked it up in detail on their computer database.

 

[SunlitComet]

tsb says you can you can use synthetic just keep on eye out for leaks thru rtv sealant if used on the gasket. gt4 means 3.73 gear ratio. an additional g80 code would mean the carrier is a g80 locker unit and not a plain open carrier. at any rate the g80 did not use friction material to require a modifier. use the gasket available and some gasket sealer. that should let you use synthetic without trouble. there was some concern that sythetic gear oil attack rtv sealant creating leaks. synthetics have come a long way since 1998. and ls is supposed to meet gl-5 needs as well. use the mobil ls stuff and the gasket with some gasket sealer and just keep an eye on it. you should be fine.

 

[joe90]

What viscosity?

 

[SunlitComet]

75w-90.

 

[joe90]

What side of the gasket do you put the ATv? On the cover or the axle side?
Also, how long do I let the atv cure before adding fluid? Package says 24 hrs.
Also, what torque for the cover bolts?

 

[SunlitComet]

both sides. and use a gasket sealant on the gasket not rtv and follow instructions on package. 20 ft. lbs.

 

[joe90]

Too late , i put it on the cover side only and buried the bolts with mt 1/2 impact. That is what i hate about the internet and email. it can take days for an answer when i could have had all this fgured out with a 2 minute phone call. now log do I wait until I ad fluid or should I drive it to work now and get my answer later here.

 

[SunlitComet]

well since you used a 1/2 impact gone on cover bolts i say go for the gold and fill it now. cant get any worse i think.