Best oil for diffs and Transfer Case

[Kushog]

I am looking at changing the oil in the front and rear diffs and the transfer case as well. Any recommendations on what oil to use and what to stay away from.
Rick

 

[Z15]

What year and model truck? What kind of transfer case, shift on the floor, push button or rotary dial?

Here a site to look up capacities ---->Application Guide

 

[Kushog]

It is a 2008 GMC Sierra Crew Cab iwht the flex fuel. It has the rotary dial with the auto trac option.

 

[Z15]

front and rear differential use 75W-90 synthetic GL5 gear lube
transfer case uses Dexron VI ATF, same as the auto trans (synthetic)

AMSOIL would the best choice IMO and that all I have in my 2010 Sierra and Cadillac. There are cheaper lubes but none better IMO.


Mike
2010 GMC Sierra SLT ECSB All Terrain Z71
2009 CTS4 AWG Performance Sedan

 

[Kushog]

Are there any additives that should be put in with the oil in the diff?

 

[Kushog]

How to find out if you have 4 or 6 speed trans.

 

[Z15]

NO. do not use any additives in the rear differential. Additives are ONLY used in G80 Limited Slip Differentials which are installed in CARS, not GM trucks. If you do use an additive it can lead to problems in the G80 Locking Rear Differential, if so equipped.

Lock at the shift indicator, the 6 sp trans looks like this PRNDM

and the shift handle has the +/- to shift up/down when in Manual Mode

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. 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.

2010 GMC Sierra SLT ECSB Z71 All Terrain
2009 CTS4 AWD Performance Sedan

 

[Kushog]

Thanks for all the info Z15. I also have a 2008 Cadillac CTS4 3.6DI . Do you have a link to a good forum for the Cadillac. Thanks once again.
Rick

 

[Z15]

Nice

This is the best site http://www.cadillacforums.com/forums/2008-cadillac-cts-general-discussion/

My car has every option but the DI engine, could not find one in stock at the time the deals were on. Been a great car, no problems. Will be 3 yrs old in Jan 2012 and has 21,000 miles. In storage for the winter, snow on ground here along Lake Superior and they are salting the road.
I had a 2005 prior.

I just love the $995 Blue Diamond Paint

 

[Kushog]

Beautiful car, really like the car.