All the craziness I have read about changing gear lube every 30, 000 miles and using some special synthetic oil in them. What about all the hundreds of thousands of rear ends that have run forever as long as you kept the fluid level up in them. A little reality folks.

 

You'll never go wrong changing oil as long as its done correctly.

 

The differential oil is fine at 90-100K intervals if the differential is in good order. I did one drain at 60K to check and it was a long way off from needing service.

 

I'd say you have more risk on a differential on having a leak- then running out of oil. That will kill a transfer case more than anything else. Not a whole lot of oil in them.