Recommended gear oil?

Dirk Aden

Dirk Aden

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Joined
Mar 30, 2018
Messages
2
Location
Colorado Springs, CO, USA
Fellow Jeepers-
I am about to replace a leaky Differential on my 98. I found the gear ratio tag, but I was wondering what type of gear oil would be best for a 4.0L w/ auto trans. I noticed there are a few types. I just want to make sure it's correct.

Thanks in advance!
 
Dirk Aden said:
Fellow Jeepers-
I am about to replace a leaky Differential on my 98. I found the gear ratio tag, but I was wondering what type of gear oil would be best for a 4.0L w/ auto trans. I noticed there are a few types. I just want to make sure it's correct.

Thanks in advance!
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Your axles are decidedly not fussy about the gear lube they run on so long as it is a GL-5 gear lube which is what 99.999% of them are. If you tow a trailer, a heavier viscosity like an 80W-120 or 85W-140 is perfect. If you don't tow, a 75W-90 or 80W-90 is fine, or you can go with an 80W-120 etc. In other words, the exact viscosity is not important. Just lean towards one of the higher viscosity gear lubes if you tow a trailer like I do, otherwise the exact viscosity doesn't really matter.

And since pretty much all the GL-5 gear lubes you'll find on the store shelves also contain a friction modifier additive required for axles with the Tracloc limited slip differential which your axle may or may not have, you don't also need to add that additive separately if you know you have the Tracloc. If you don't have a Tracloc in your rear axle, it's still ok to run a gear lube with that additive since it is compatible either way. :)
 
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The Walmart house brand synthetic was pretty well thought of when I was doing my research a while back.
 
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Mr. Bills said:
FYI for anyone who reads the study - It was commissioned by and paid for by Amsoil.

If anyone thinks that it is coincidence that Amsoil scored highest of the gear oils tested should contact me immediately. I have some swamp land and a bridge that you might want to buy.
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you beat me to it, i was just gonna say after i posted that, now i didnt look to see who did the study:) now on that note, if you knew you had the best, nobody else is gonna wanna spend the money to study it.....:)

i have nothing to do with amsoil:)
 
My kids drives them off to college and so, was neglected. I was meticulous when my rigs are still with me (the kids were high schoolers then.
 
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TJ2 said:
Cliffish gets bored easy. 10k is way too early. I say 100k is ideal if you don't off road.
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I know it is my OCD...I change the synthetic oil (not in my TJ) every 5K...on my wife's benz it really a challenge to go 7500 miles even though book says 10K...well no one ever killed an engine by changing the oil too often.
 
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SamRI said:
Has anyone used BG products ?
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We used their diff oil additive for aggressive limited slips that chattered a bunch. Worked great.

We used to see diffs from 60's era vehicles with the old original "whale oil" as we called it. Dark, thick, stanky, and the gear set looked like new.
 
I just changed engine oil.. as in tuesday.... is it weird that I want to change it again just to flush out as much crap as possible?
 
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