Is it normal for a BMW to use/consume oil? Newbie BMW owner. '06 330i w/sport, premium, cold weather packages, (N52 engine?)...bought the car CPO in April '10 and after roughly 6,000 miles I was a quart low, this was MAYBE 2 months ago that I got the warning light and roughly less then 2,000 miles later and the oil level is reading lower then when I topped it off (expecting the light to come on probably in 2 more months. Car is a daily driver, decent amount of stop and go traffic but nothing out of the norm for South Eastern PA. I also noticed the car has a noticeably rough idle to it, when the oil was topped off last, the rough idle went away. Any advice, tips, possible causes are greatly appreciated.