2006 bmw 330i with the NA N52 straight 6. I have previously been using longlife-01 Castrol 0w30 and switched to longlife-01 Castrol 0w40 since its cheaper, available locally, and so i can just buy one type of oil for it and the old m3. I have have noticed around another quart of oil consumption over 10k miles with the 0w40. This question is more of a curiosity if a thicker oil could burn at a higher rate than a thinner oil. In my case it is possible that theres something else like the weeping oil pan got worse (though i havent noticed spots on driveway).