I drove cross country to NJ from San Diego. When I got there I had new batteries put in, new seals on the differentials, oil change and Transmission fluid change. I asked to have the transfer case drained and refilled but the service manager said the fluid was pristine and there was no reason to change it. When I returned home the San Diego Dodge dealer said the fluid had to be changed because of time/miles even though I had not used 4 wheel drive more than a few times. Who is right, I don't believe that the fluid goes bad because of time or miles (not put on it.)

 

You are using the transfercase every time you drive. Things are spinning and friction is causing the fluid to break down. How many miles are on the truck? I don't have the owners manual by me but IIRC the fluid is recommended to be changed at 50k miles. If you are at or over that I would change it.

 

I would change it. Your only looking at about 20 dollars worth of oil and 1/2 labor at the most. The transfer case turns all the time wether or not it is in four wheel drive