I know this is a VERY controversial subject and I wouldn't like anyone to think I am recomending any particular method.
My 7 is off for its PBC today and I took it for a run early this morning - "Honest officer, I was just bedding-in the brakes". Following certain running-in suggestions, I gave it "some welly", both accelerating and letting it overrun, in all gears. Didn't go over 5,000, well maybe once 😬. Ran it for about 20 miles, bedding in the brakes at the same time, then did an oil (GTX £9.99 for 5 ltr) and filter change.
The oil seemed to contain VERY fine metalic dust. I couldn't feel it by rubbing it between my fingers and haven't yet checked whether it's ferous or not. The contents of the oil filter was more concentrated. On the whole, I'm glad I carried out this procedure. What the long term result will be - who knows?
The theory is that, not killing the engine, but not babying it either, for the first 20 miles really lets the combustion pressure seat the rings against the bore walls and beds them in properly. The non sythetic oil is less slippery and aids this process. The quick oil and filter change is to get rid of the "carp". It looks to have worked - assuming the dust was bore and ring steel and not somthing more sinister - powdered engine anyone?
BRG SV 😬 Boxes empty, car full