It's a 2.5 liter, M54 motor in a BMW E46. It had been using about a quart per 1000 miles--which is okay according to BMW --and is using much less after I modified the PCV system. After 1200 miles, the dipstick has gone down 1/4. I'm currently using M1 HM 10w40, which wasn't having any effect on consumption before the PCV modification. I also ran a Liqui-Moly idle flush before changing the old oil--also M1 HM 10w40--and added a bottle of MoS2 to the new oil. In my opinion, the PCV modification is the most likely cause for the decrease in consumption. It's a modification to increase crankcase pressure that many people have successfully performed on this motor to stop or decrease consumption. The problem here is that I'm not thrilled with the idea of running a 10w40 HM oil over winter. It's my understanding that the HM oils tend to be even thicker than regular oils, and I'm already using a 10 winter weight in a car that calls for 5w30. I'm currently looking at: Rotella T6 5w40, M1 TDT 5w40, M1 0w40, and Castrol Edge 0w40. I would like to stick with Mobil 1, due to the current rebate. But I'm open to using one of the other oils if you think they would be better for winter, or a suggestion that isn't on my list. I'm not really interested in Redline or Amsoil, etc, and want something I can buy locally for a reasonable price. I don't plan to keep it in the car for more than 5k miles. Thanks!