Ran the crap out of it, 230 miles. When I refilled the diff I came up about a pint short of fluid. Sitting here was an unopened 20+ year old bottle of Slick 50 diff fluid. Topped it with that. Damn if it isn't noticeably less clunky Had to do a quick merge for a few miles of road driving. I can report it pulled nicely to 5k in third and had plenty left..