Gosh, that's the $64K question. It depends on your driving conditions, environment, style, etc. For me I ran the MC on the V6 out to about 5000-5500 miles...that's as far as I was willing to take it. The first and only UOA I did came back great. (Now using PP.)As a very general rule, 5000 miles is a good OCI. It's longer than the typically wasteful 3K change, but it's not so long that you have much chance of over-stressing the oil and add packs.Now if you are flogging the hell out of it with lots of WOT, high-rpms, racing, high-heat operations, dirty/dusty environment, towing and hauling a lot, etc., then I'd change it sooner.The best way to know for sure is to do a few UOAs and see how it measures and trends.
