Rear Differential Lube Change Interval

[HBarlow]

This comment I'm going to make is not based on laboratory testing or lube oil engineering, just my own personal observation.

I installed a Mag-Hytec finned aluminum differential cover on my '06 when it was only days old and had 300 miles on the odometer. I was transporting RVs at the time and very quickly put 230,000 miles on the odometer.

As every Gen III owner probably know, the owner's manuals for these trucks specifies a 15,000 mile differential fluid change. I stubbornly resisted that requirement, particularly because I was putting almost that many miles on the truck each and every month.

After changing it once at around 25k miles, on the recommendation of my mechanic buddy who formerly worked several years in a Dodge dealership, I extended the change interval to 50k miles. I continued to do that without adverse effects for the almost two years and 230k total miles I owned the truck.

When I bought the new '08 I moved the Mag-Hytec cover to the new truck and just did the first differential lube change last weekend at 48k miles. The fluid was pristinely clean and there was only the tiniest amount of metal "fuzz" on the magnetic plug. I'm not towing every day with this truck like I did with the previous one but have done some towing.

In my personal opinion, it is reasonably safe to extend the differential fluid change interval to 50k if you use quality brand name synthetic fluid and have a Mag-Hytec or other brand deep finned aluminum cover.

ON EDIT: After reading a number of follow-on posts by other members who mentioned the importance of a first service, perhaps at a much lower mileage, I remembered an important detail I had overlooked. A member suggested I return and edit this post to mention an early lube service I had forgotten so here it is:

My differential was actually serviced at 350 miles, the distance from my preferred dealer back home. The OEM differential cover was removed, the factory fill was drained, and the Mag-Hytec finned aluminum cover installed. Seven fresh quarts of synthetic lube were added.

The first drain may have allowed sufficient break-in to allow new parts to wear in with each other and the early first drain may have flushed out any tiny wear particles or "debris" left over from the manufacturing and assembly process.

It might be wise for anyone w/Mag-Hytec cover who is contemplating extended service intervals to perform the first service as recommended by the manufacturer.

I'm not encouraging anyone to follow my extended service procedure. It might be considered neglect by AAM, the manufacturer. It is what I do and I have not found any negative results from my decision. Your results may vary.