Posing this question to see just how high someone may be turning the Dmax. Reason being I got caught a little off guard decending a 9% grade into Death Valley California about a month or so back. The rpm's hit 4500 and I would stand on the brakes for about 10 seconds and release them for 10 seconds this would only drop the speed by 10 mph and after 10 seconds of no braking with my foot the truck and 5er would pick back up the 10 mph I had managed to scrubb off. I had to continue that process for I think 6 miles of grade, it was a little bit disturbing since I knew the Allison would automatically upshift at 4800 to save the engine. It spent what seemed to be 15 minutes of turning between 3800 and 4500 rmps. That evening I checked the oil and it had blown out 1/2 quart of oil. It has never used oil before and has not used any in the next 8000 miles of towing. Do you suppose I hurt anything in the engine by turning it that high for so long a time, or is that just nothing to worry about?