i have a question my transfer case says it takes atf fluid but the person who had the truck before me put gear oil in it. what could that do to my transfer case. just asking.What would be a good type of atf fluid to use?

 

Is that stamped on the side of your transfer case? I've never seen that, maybe because mine is always covered with mud.

 

The transfercase in my 80 Bronco used gear oil, just like a manual tranny. I'm not sure what newer ones are using. I'm sure the owners manual or a internet search will answer your question. Posting the year of your truck would help.

 

Newer ones use ATF

Both my 91 F250 and 97F150 use ATF.

Check your owners manual for the type, but both of mine use Mercon

 

If your transfercase uses ATF and someone put gear lube in it you should drain it, flush it, and start with new fluid. Gear lube is much thicker than ATF.