When I took delivery of my '05 M6 in June with 18 miles on the odometer, there was a small amount of lifter noise for a couple of seconds when I started it for the first time (cold engine).
Occasionally, since then, the lifter noise would occur on a cold engine start, lasting a second or two.
Since changing the oil the first time at about 3,300 miles and installing Mobil 1 5W-30 and an AC Delco PF 46 filter, the noise has not occurred, even with cooler weather which would normally make it more apt to happen.
Now I am wondering if the factory installed a lighter weight oil to facilitate break-in, which, if so, may have caused the lifters to be more prone to leak down with the engine not running.
BTW, the level was still at the full mark, and the oil was fairly clean, with none added, when I changed it, which is encouraging.
Has anyone else encountered this situation with lifter noise?