I read in an earlier post about a member mentioning a "rattle" or ticking noise when cold - usually in the AMs - waiting for oil to circulate throughout engine to lifters, cams and upper cylinder. And thought I'ld pass this on
Talking with some old BMW tech friends - it came up and they're using (w/BMW's blessings) a product -> Lucas Synthetic Oil Stabilizer with a 95% sucess rate. Depending on the mileage - they say it leaves a slick coating on engine parts & prevents that "dry start" noise/wear. It's compatiable with all oils, synthetic & non-syn and you only have to use it once. Some really high-mileage and abused engines have too much wear and should be lQQked into. They advised staying away from the Slick 50s, "motor miracles" & tune up in a can.
I'm not a fan of "miracle in a can" or additives but coming from these guys who crawl around these things all day - I tend to trust their recommendations. (Trust me - these guys are factory BMWs' biggest critics because they have to deal with "imperfections" daily)