Most SUV manufacturers recommend changing the rear differential oil on their models as part of the routine maintenance regimen. Depending on your specific make and model SUV, the frequency of this oil change may range from 12,000 to 40,000 miles. When used under severe conditions (towing/off-road), the differential oil should be changed more frequently.
Some SUV's, such as the Mercedes-Benz GL class vehicles, state in the owner's manual that the real axle differential units are sealed units and contain a lifetime fill. The only recommendation is to check the differential housing visually for leaks, which would indicate a need for repairs. Aside from such component damage, changing the oil is never required.
There is a wide variance among what SUV manufacturers suggest as proper care and maintenance for the differential units in their vehicles. The best policy is to abide by the maintenance recommendations stated in the owner's manual for your particular vehicle. Because engineering specifications vary widely, what is "proper" maintenance for one SUV may be considered owner neglect by another manufacturer.
