A collector I know with a substantial collection (not near the size of Leno's) uses a quart of 30-weight motor oil for every 10-gallons of gasoline in his pieces that are started and brought up to operating temp every 90-days to keep gaskets serviceable. He says that's the only method he's found that stabilizes gasoline for long periods of time. On his museum and long-term storage pieces there is no gasoline in the systems.
