I have a 2003 250SD 4x4 and I was just told that I should run my truck in 4 wheel drive every now and then to keep the gears lubed.I hav'nt driven it in 4 wheel drive since I purchased it a year ago. I do not go off road at all, just tow my bumper pull rv and drive it around town. Thanks as always you guys are great. Bob

 

That is good advice. By doing so you keep everything lubed in the front axle, otherwise the gear oil just lays in the bottom of the housing. I run mine at least once a month in warm weather, in the winter time my front hubs are locked in 99% of the time so the axle is always turning.

 

Not only the lube issue, but if you have ESOF, it's probably a good idea so that the actuator gets some use.