Why change the oil in the front differential. I only use the 4x4 about 5% of the time. I know the drive shaft spins all the time but there is no load. I check the level but have not changed it in 70,000 miles.

 

I feel the same way. Just run synthetic in it and plan on not changing it for at least 100k, I use Royal Purple. Not sure on the newer trucks but on the 12 valves the manual says both the differentials are lubed for life if you aren't towing. Don't think I'd go that far but 100k seems reasonable.
Good to check it at every oil change though, once mine turned milky, turned out a rock had cracked the 4wd actuator and was letting water in.

 

I wouldn't change it if I had a C.A.D. set up because it is open exept when in 4x4. But mine was built after JAN of 02 so I don't have this option.

 

The one and only reason for changing the oil in a front diff on a part time 4x4 is moisture. Moisture and condensation can get into the oil and cause bearing problems - ESPECIALLY on infrequently used front diffs.....On trucks that don't see any offroad use, I would suggest changing the oil every 2 years to be safe.....don't waste your money on synthetics for the front.....the front is used so little and runs at much lower temperatures, that there will no benefit.....also, synthetics do not suspend moisture any better than extreme pressure gear oil.

 

Thanks for that info CTD NUT, that's great to know. Might need to get mine changed soon.

 

Even with the CAD the spyder gears turn all the time unless it is in 4wd. The left axle turns them.