synthetic oil for transfer case?

Hey all, Wondering why ATF is used in the transfer case instead of a lightweight oil. I know ATF has hydraulic properties and cleaning additives. As far as I can tell, its just thinner than motor oil. What if I were to use a light motor oil in the TC such as mobil 1 0W-20? Should be a better lubricant than ATF right? Only reason I'm considering doing this is because my TC has about 160k, and I'm sure the allowances have increased considerably (it makes some noises when you let off the gas).
Thoughts?
TIA.

Use ATF, oil is too thick to be pumped by the transfer case's pump.

Wow, theres actually a mechanical pump in there? Why is it used? Does it pump lubricant up to the top of the case?

962drrhino said:

Wow, theres actually a mechanical pump in there? Why is it used? Does it pump lubricant up to the top of the case?

Click to expand...

Yes. To lubricate the chain and other internal parts of the transfer case.

Take a look at numbers 29 and 39-43 on the diagram here: http://www.pgh-offroad.com/forum/showthread.php?p=102141

I'd stay with ATF. Pretty hard to argue with design engineers on this one.

Thanks joe!! Yup ATF it is. I'll probably switch to ATF synthetic when I change it next.