I want to change the fluid in my transfer case. What size hex wrench is needed for the drain and fill plugs.

Thanks.

 

It's a 3/8"

 

Thanks much.

I changed out the fluid in my differentials today and used Amsoil Severe Gear 75w110. I think next time I'll get aftermarket diff covers that have drain plugs. I'll be more apt to change it regularly if I can do it quickly. I don't always have a lot of time for this. The oil that came out looked pretty good except that there was black residue on the internals. Is that normal?

I also changed the motor oil today using M1 Turbo Diesel Truck 5w40. Based on recommendations of others here, I had bought a heavier duty drain plug with magnet from Geno's. Turns out that was a good move as the factory drain plug was cracked. That factory drain plug is a POC.