i did my oil today and when i checked it in the morning it was at teh minumom mark. whan i did the change like a month and a half ago it was at the full mark. my car only has 50,000 miles on it and it doesnt even smoek or anything. so im guessing its just evaporated oil goign through the pcv as usual. and normal oil break down. plus a lot is in the filter when i do the change.