Diff and x-fer case service interval

[D60]

The pump rub eventually shows up as a hole in the case and you'll know because you will have a leak on the top right side. I had it happen on my Denali with the 149 t-case leaked but never any mechanical issues.

That's exactly my point, you don't want it to get as far as a hole so you have to just fly blind and forget about it or lay eyes on the internal castles. You'll see them starting to get notched from the pump plate banging around.

 

[D60]

One common theme being said in this post that is wrong is basing the oil change interval of the transfer case on how much he is using 4WD. That makes no difference because the T-CASE is running the same no matter what range it's operating in. It is always transferring power.

We can agree to disagree but running Auto allows slippage of the friction plates (which are just automatic trans discs) so you get (more) friction material in the fluid. This is also what the special fluid does, ie dampen chatter

Yes, it's always pumping that fluid and transferring power but it's not a straight mechanical connection like a more "primitive" case.

Even in 4lock where it mashes the clutches tight they CAN slip if you're stuck and really working to get out of a hole or something. No different than a manual trans clutch slipping, really. Plenty of JL's with the "AWD" case burn up the clutches trying to escape a bad situation

 

[GMBoy]

We can agree to disagree but running Auto allows slippage of the friction plates (which are just automatic trans discs) so you get (more) friction material in the fluid. This is also what the special fluid does, ie dampen chatter

Yes, it's always pumping that fluid and transferring power but it's not a straight mechanical connection like a more "primitive" case.

Even in 4lock where it mashes the clutches tight they CAN slip if you're stuck and really working to get out of a hole or something. No different than a manual trans clutch slipping, really. Plenty of JL's with the "AWD" case burn up the clutches trying to escape a bad situation

I can admit when I am wrong - I totally forgot the 4auto mode. I stand corrected.

 

[thastinger]

I do all of ours at 30K. I'm sure diff gear oil could go much longer, especially the front diff, but that interval has always worked for us and we keep vehicles over 20 years each. We have 2 traditions 4x4 drivelines with traditional transfer cases and one AWD with a PTU style transfer.