2 gallons will cause some wear, but mixed in with the tank it's not the worst thing as long as you don't do it on a regular basis. you tried it, it burned, don't do it again.
some members here have centrifugal cleaners for the oil, and they soot filter it, and use it as a fuel...
I'd not recommend it...

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!