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75w-85 in Rear Differential???

SavageSierra

By SavageSierra
in Engines & Drivetrain

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Eddie 70 Senior Enthusiast

Eddie 70

Posted
Posted

Just left Autozone and could not find any 75w85 just like you guys were saying. I did find 75W90 in Lucas, M1, Royal Purple. The M1 says 75W90LS. Makes me think it's for Limited Slip. From what I understand, a lot of these trucks no longer have LS differentials in them.. Mine says G80 on the option list which is the locker.

 

What are you using for the G80 diff's?

Dozer466 Enthusiast

Dozer466

Posted
Posted

Oreilys has 80w90 that's a non synthetic with no limited slip friction modifier in it. I forget the name of it but it's in a black bottle.

 

 

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07Softail Senior Enthusiast

07Softail

Posted
Posted
I use 75w-90 and have changed the lube twice and my truck has less than 8000 miles. No synthetic here... the diff works a lot better with mineral base oil.

 

 

I'm NOT challenging your claim, but I'm curious how it works better.

The clutches in the diff don't chatter as bad with mineral based oil.

 

RT

Colossus Senior Enthusiast

Colossus

Posted
Posted

Very important note there- don't be using those things with limited slip friction modifier additives for you boys with the G80. I recall many folks on here years back cussing up a storm after doing diff service and the rear end went crazy. Turned out they were not using the right fluid and those limited slip modifier caused all kinds of hell.

Ya'll remember that. It will prove to be very helpful to many folks on here over the years.

Brianibew Enthusiast

Brianibew

Posted
Posted

Just left Autozone and could not find any 75w85 just like you guys were saying. I did find 75W90 in Lucas, M1, Royal Purple. The M1 says 75W90LS. Makes me think it's for Limited Slip. From what I understand, a lot of these trucks no longer have LS differentials in them.. Mine says G80 on the option list which is the locker.

 

What are you using for the G80 diff's?

 

I've used Mobile 1 LS gear oil for years with no issue in my G80. I would have no issue using it again.

Cowpie Senior Enthusiast

Cowpie

Posted
Posted

My preference is to stop at a commercial truck supply place, commercial truck dealership parts dept, etc and pick up the best stuff on the shelf..... Mobil Delvac 1 75w90 synthetic. Gold and black squeeze bottles just like the LS stuff comes in. A better product with broader application (including light trucks) than the LS variety, which has only a GL-5 application. Meets all major OEM approvals and is designed for use for 500,000 miles in commercial heavy truck differentials. It is the most common factory fill diff lube for heavy commercial trucks, and the differential OEM's will extend the base warranty by 50%, from 500,000 miles to 750,000 miles by using it. It is more than up to being able to handle anything that anyone can throw at it in a pickup diff.

07Softail Senior Enthusiast

07Softail

Posted
Posted

Just left Autozone and could not find any 75w85 just like you guys were saying. I did find 75W90 in Lucas, M1, Royal Purple. The M1 says 75W90LS. Makes me think it's for Limited Slip. From what I understand, a lot of these trucks no longer have LS differentials in them.. Mine says G80 on the option list which is the locker.

 

What are you using for the G80 diff's?

G80's still have clutch frictions and steels.

 

RT

  • 2 months later...
Black02Silverado Senior Enthusiast

Black02Silverado

Posted
Posted

I can't find the long version of this, only what another AMSOIL dealer has posted on YouTube. But thought you all would find it interesting. This was a long time ago and shows that back then AMSOIL's gear lubricant was tough, fast forward to todays technology and their ability to improve on that formula.

 

 

  • 2 weeks later...
Zasker1 Enthusiast

Zasker1

Posted
Posted

I used Royal Purple 75w-90 at 48000 miles it probably didn't need it but I've done a lot of telling I want to see just how many metal shavings were in there

 

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