I've told this story before, but when I was a bicycle ridin idiot kid, I used to ride over to see this OLD guy who ran a service station way further than I was supposed to ride my bike. lol I've seen him drain all the old oil out and fill it back up with 100% diesel fuel, start it and let it run for like 30 minutes. It was the blackest chit you ever saw comin out. lol Then he'd put a new filter on and fill it up with oil. Old man Balkom was his name. He said that's how he'd done it since he was a kid and that was probably about the turn of the 20th century, cause he was OLD and this was probably 72 or 73.