ok, so I had my front and rear differential fluids as well as transfer case fluid replaced. the used 75w/90 supersyn iii with LSD additive in all three. is this correct? the service manual says dexron vi for the transfer case. which is correct? this is in a caddy dealer and the service guy said it is what they use for the transfer case. is this correct hillbilly?

 

a $400+ service btw!

 

Transfer cases have been ATF for years now. I don't know where the gear lube idea is coming from. The axles came with synthetic smelly gear lube.

 

how do they flush out the differential in there? flush it with the dexron vii. will a mixture mess up the transfer case? like in the tranny? where oil contamination is serious business?

 

I believe the transfer case has a drain plug. The gear lube may have had clutch "stuff" but a drain when warm to hot followed by a fill with the right Dex 6 and a flush should do it. Maybe Dex 3 for flush to save a little $. The 4WD Auto clutch is supposed to apply in a quarter second or less but only in Auto and when axle-to-axle slip is detected. As such there isn't an inter-axle differential any more like the AWD cousin and older "Full Time" systems.

In Auto it is like locking in the old school front hubs. Both front axle half shafts, differential, and front drive shaft are all rotating close to rear shaft speeds. If slip is detected the clutch grabs.

I still don't get why they still insisted on gear lube. Fluids are spelled out in owner's manuals.

The trans has clutches that apply thousands of times. The right fluid is much more important there.
No big deal but an expensive nuisance.

 

they said it is what they use in all escalades hybrid and non-hybrid, really? the BG rep promoted it and said warranties it(transfer case )for lifetime if replaced at 75k which isn't realistic since replacement is at 100k miles. So, they will drain and flush it and replace it with A/C Delco dexron VI. what a nuisance.

 

The thicker axle lube most likely won't break anything. However, the viscous spin losses will add drag and cost some fuel. Most will never notice but you are putting some serious miles on that ride.

Torque * rpm = power. Thicker heavier lube = torque. Driving = rpm.

 

finally dealer change it to A/C delco dexron VI.