Well Airknight I'm no "oil expert" by any means, but if its real cold outside and you start your car wouldn't it make sense to have "0" weight at start up instead of "5" weight
Besides, we are talking about sythetic here, which from what I've been told/learned is refined thinner than convential oils. That being said, maybe those guys with diesels should change over to a synthetic 10W40 grade which Mobil doesn't make. In the summer I'd run Mobil 1 15W50 in those diesels and let it ride
