Originally Posted by ebrobb

Should I return the 5w-30 in exchange for 0w-40 or is it that important?? And what of the 10000 mile interval, my Father in law (a retired GM mechanic) always swore by 3000 mile intervals, only a few years ago did I convince him to switch to the 5000 interval. 10000 makes my cheeks tighten, somewhat. Although, since the oil is so expensive and the truck holds almost double the amount of most other makes with similar sized engine, it must be OK.
Advice appreciated, Thanks Eric

99 ML430-95,000 miles