I've stripped 3 of the plastic diff gears and one set of planet gears when I tried the 300k diff fluid. Went back to the grease in the diff and the plant gears are fine. Granted the tires are usually spinning and throwing grass, rocks and dirt but for whaqtever reason a 7 cell pack just destroys the diff gears. I stripped one in less than one charge once. With 6 cell packs it'll last seemingly forever though. But as strange as it sounds, the spur gear is still the stock one the truck had when I got it.