Hmm...I'm spending WAY too much time here. Found you guys just the other day. I have an '04 Porsche Cayenne Turbo. It's equipped with the 4.5L twin-turbod V8. Porsche recommends M1 for all its cars and for the C-T, 0W-40 for ambient temps below -13dF/-24dC and 0W-40 or 5W-40 or 5W-50 for ambient temps above -13dF/-25dC. Based on the many notes I’ve read, I’m now thinking there may be a better way than just following Porsche’s recommendation. I believe strongly in changing oil and filters in new engines the same way the Democrats vote in Cook county--early and often. I drained the factory-filled M1 0W-40 and the filter at 33 miles, filled with dead-dino (Mobil) 5W-30, and drained and refilled again at about 300 miles. Followed the break-in recommendations here http://www.mototuneusa.com/break_in_secrets.htm for the first 200 or so miles. At about 1900 miles refilled with M1 0W-40. Haven’t changed again thru about 9500 miles. Altho Porsche recommends changing oil and filter every 20,000 miles, I’m now thinking about changing twice a year and using a slightly less-thin oil for summer. If I stay with M1, they’d be the 0W-40 for the cool season (I live in Phoenix and we don’t have winter, just 6 months of summer and 3 each of spring and fall) and whichever of the 5W-nns I can find for the summer six months. I’ve used and loved Red Line gear and transmission lubes for decades and would consider their engine oil, but they have ‘only’ a 5W-30 in the ranges I could use. Anyone have an opinion here? Should I consider something other than M1 and Red Line? In your responses, pls include URLs for the people like me who don't know what the undefined acronyms mean. --------------------------- Speaking of undefined acronyms, what’s the ‘GC’ that I see frequently here?