The SDI's get 20 mpg (for the sake of easy calculations). Carbed get 10 (for the sake of easy calculations). One quart of oil to a tank of gas gives you about a 40/1 ratio. On that tank of gas the SDI goes 200 miles and the carbed goes 100 miles. All things being fairly equal the SDI engine has turned twice the rpm's that the carbed one has on the same amount of oil. I don't think this is a good thing. My dealer set the oil pump to a quart of oil to a tank of gas which is still lean if you look at it this way but the plugs are looking black not tan so I'm going to go with this for a while. No fouled plugs yet but only 500 miles on it. I hope this doesn't open a can of worms but just curious about your thoughts.