GM 2500/3500HD Transfer Case Service

Updated Dec 11, 2014

Transfer Case fluid_BS25991Transfer Case Service Tips For GM 2500/3500HD 4x4s 

Four-wheel-drive pickups need to have the transfer case checked just as one would differentials and the transmission.

Some younger mechanics overlook it, says Alabama GM master technician Rod Halsten.

GM recommends the transfer case fluid be changed out every 50,000 miles for severe service applications.

Severe service in the heavy construction, mining and road building or towing applications means any time four-wheel-drive is engaged more than a couple times a month or the vehicle is used in dusty, sandy, muddy environments.

Halsten says its critical to use use AC Delco Auto-Trak II fluid (bluish color) in the transfer case.

The veteran GM diesel tech warns to not use Dexron VI ATF, which is reddish in color, or low-viscosity gear oil as some HD owners have tried. Doing so will cause serious damage to the transfer case.