recommended differential fluid

[chauncey0337]

I have a 2000 tahoe lt 4.3l, 4x4. I went to local auto parts store and the guy behind the counter told me there a few recommended diff fluid weights depending on the vehicle but he didn't know which one I needed. Can somebody here help me. I need to do front and rear diffs and transfer case. Thanks.

 

[afpj]

It should be in chapter 7 of the manual. Our 2002 Yukon 5.3 L 4 x 4 takes 75W – 90 synthetic for rear diff, 80w-90 for front, and autotrak II for TC. Iirc 2003 is when they had other options for the tc. Someone else may chime in for greater detail...

Have you called a dealer parts desk to ask what fluid? They usually just need last 8 digits of vin.

 

[chauncey0337]

Thanks Bob. I'll check my manual if I can find it.

 

[Sasquatch]

The manual says 80-90 for the front and 75-90 for the rear. I used 75-90 royal purple in both front and rear a few years ago with no problems.

 

[Donnie Yukonie]

If you guys are running the G80 I thought there was a friction modifier you had to add to the rear axle if I'm not mistaken

 

[YukonXL04]

There is. Some of the synthetic fluids have it included though.

 

[Sasquatch]

This is from a GM bulletin on the subject.

LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849).

The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

 

[YukonXL04]

That's great info. Thanks. I have the g80.

 

[papito]

great time... im going to change mines as well in a 06 denali xl.. was thinking of doing the royal purple but everyone tells me amsoil is the way to go.. the only problem I have is no parts store carry it around me.. should I just buy fluid from dealer or use the royal purple?