I've got just under 100,000 miles on my ML320. I only change oil when the computer says to, but I always use Mobil 1. Car has never had anything but Mobil 1 except during initial break in. About 40,000 of the miles were pulling an RV trailer. Never have had to add oil between changes, in fact it has never even gotten a quart low, let alone the two quarts required to "get down to" the fill line.