I'm in FLA, no such thing as a cold start here.. and I have a considerable supply of 15W40 on hand, which carries the SN cert as well as the CK rating... so is there any real point in purchasing and using the recommended 5w30 or does it make sense to use the 15w40 since I have plenty of it and it make the oil change free.. I dont think it makes any difference but it would be interesting to read some of the commentary and doom and gloom.