Mixing oils..... slightly.

[Bevel bob]

I have heard of people puffing some into the intake and later doing a couple of oil changes to clear away.

[blethermaskite]

Further to the subject of bedding in rings.....an old friend of mine who raced Manx Nortons had his own method, he had a spare engine bottom end and would fit it with his race engine barrel his new rings and an old piston, he would then lube the piston rings with brasso metal polish and run this 'special' bottom half with an electric motor for about five minutes. He said after a bit of a practice lap that was the rings bedded in
Cheers George