Dear Tom and Ray:

After the boating season, I sometimes have two to four gallons of gas mixed with outboard motor oil. I like to start fresh in the spring. Can I run the old gas through my car if I use a gallon or two per tankful, and fill the rest of the tank with fresh gas to dilute it?
Moose

TOM: Sure, Moose. Most outboard motors require a gas/oil mixture in a ratio of something like 50:1. So there's really not much oil there to begin with.

RAY: And people used to (and some still do) dump mystery oils and potions into their gas tanks in hopes that these oils will do things like lubricate the top end of their engine and make their fuzzy dice softer.

TOM: Whether these "mystery" oils do any good is not clear. But I think we can safely advise you that putting a small amount of oil in your gasoline once a year won't do your engine any harm.

RAY: Of course, just to be on the safe side, you might want to do what my brother did last time he found himself in this situation; he tried the gas in his wife's car first.