So the shop I go to just put in Total 10w 50 claiming it did better than Castro 10w 60 in some comparo test. I've not been able to find anything on line claiming that, but I have found ecstuning (
http://www.ecstuning.com/BMW-E90-M3-.../Oil/ES262947/) selling it. Going to the track later this week and wondering if I should make them swap it out. Does anyone have any data to back up going for castrol other than that's what everyone recommends? TIA