Originally Posted by ceb
I think he needs to check the amount of oil he drained next time.
I've changed oil for 35 years. While I don't know if 5 quarts or 8 quarts came out the other day, the drain looked 'normal'. The drain pan used in the auto hobby shop is on wheels and has a large reservoir (I'll guess 5 gallons) at the bottom. Something similar to this: http://www.amazon.com/Rolling-Collec.../dp/B004UC6NEG
I could empty the bottom container and then find how much I drain but I suspect it'll be ~6 quarts the next time I change the oil, since that's how much I put in last time. I'm not sure what such a procedure would accomplish though. Are you suggesting that less than the full amount of oil is being drained? Not exactly Occam's Razor.
I'll go with either a bad sensor or my 2008 328i holds 6 or less quarts of oil.