I changed my oil at 25 miles and 50 miles, changed it hot after a 25 mile run, lots of metal came out with the oil, the dealer changed the rear end oil cold , at 600 miles , I changed the rear end at the same time as I changed the oil , in the motor, and I changed it hot and a lot of metal came out of the rear end oil after 1,000 miles I used full synthetic oil mobil 1 5 W 50 , and # 90 oil in the rear end, again full synthetic, my Baby is a 300i Downtown