2004 differential goes out

In this day and age a lot of manufacturers of vehicles and or vehicle components do their development work with an oil supplier and this supplier makes additive changes to their product for that manufacturer. Even without government mandates purchasers of OTR vehicles are looking for mileage improvements. Do the math on 15 trucks running 100s of thousands of miles per year and a .5% increase in fuel mileage enhances the bottom line significantly. So, unfortunately, using an aftermarket/non-approved oil can have detrimental effects on the life of a component. I can give you one example that will never leave my memory banks. Our shop had an area referred to as the penthouse. It was on a separate level and accessible through a single door. The guys that worked up there never knew that there was a reason for having 2 gear oils in the overhead and only used one for diffs and transmissions. All of the differentials serviced in the penthouse started to make noise. They were putting the non-hypoid gear oil in diffs and the gears would gall slightly. On the other hand I have seen guys put hypoid oil in a manual transmission and wonder why they no longer shifted smooth. The syncros would notgrab on the gear face. One simple additive can have a profound effect on the service life of a component.