The car has been on T6 for about the last two years. Prior to that, it never had any consistency. The T6 requires either 2 gallon purchases, or a gallon and 2 quarts to get the correct amount of oil. I tried to use M1 European 0w40 and it went through oil faster than I've ever seen it. I figured this time around I'd throw some ML 10w40 in it. It has a lot of miles on it now and the car is starting to have more problems than I care to deal with. The ML is easy, not too expensive, and at least it is getting a 40w oil. The engine does leak oil, and I'm sure it is starting to see some wear so I don't think the jump from 5 to 10 is going to make as much of a difference. We will see how it does once it gets colder out. Maybe I'll switch back for the winter.