On cars that used Dino oil I used to put a quart of kerosene in for about ten minutes right before change and wow did it clear out the funk.

It's sold by the quart for the purpose of flushing out the oil, probably had some additives but I was told it's mostly kerosene

__________________
2011 E70 • N55 (me)
2012 E70 • N63 (wife)