OK, OK , before somebody jumps in and roasts me , I've done a fair bit of searching and all I'm getting right now is a headache from all the reading... What oil change interval are the people who are using Mobil1 15W50 or rotella T 5w40 (both synthetic) doing. Do you think a 7000 kilometer interval is reasonable (if not, what would you consider reasonable?) I'm pretty confident in the Mobil1 , but I don't have a lot of experience with rotella T synthetic. I know this is a very touchy subject, but I would like to have the opinions of people who are using or have used these particular oils.