Dear Tom and Ray:
My husband and I had to go out of town for work for a few weeks, so we left our 14-year-old daughter with an 18-year-old girlfriend of hers whom we trust(ed). Well, the 18-year-old brought over her boyfriend, "Einstein," without our knowledge. There was a strict no-boys policy from us, and many "Don't worries" from the two girls. They decided to try to start our Ford E250 V-8 three-quarter-ton Econoline van, which has a dead external fuel pump. Not knowing that, and seeing that the gas gauge read "Empty" (since it doesn't work either), they apparently assumed that it was out of gas. So Einstein took all the gas cans in the garage and dumped them into the van's gas tank. Living in northern Michigan, we use a variety of somewhat ancient tools, including lawn mowers, chain saws, snowblowers, etc. All of them use gas that is mixed with oil.
Now we are wondering what to do. When we replace the fuel pump, do we just top off the tank and drive? Or will the gasoline mixed with oil damage the engine? This van has two tanks, and we have yet to talk with Einstein or said girlfriend, because they have the fear of God in them and have yet to step foot in the house since we've been back. So Einstein may have put the gas-and-oil mixture in both tanks. Please feel free to laugh boisterously on our behalf, as long as you tell us whether we can drive the van.
TOM: We HAVE had a good laugh, but you'll be fine, Theresa.
RAY: When you mix oil into gasoline for a two-cycle engine, it's usually in the ratio of something like 40-to-1 or 50-to-1, gas to oil. So there's only a small amount of oil in that gas to begin with.
TOM: And I doubt there was enough fuel in those gas cans to fill up both of your van's tanks. I mean, even if Einstein poured 10 gallons of gas in there, the capacity is probably 30 gallons. So you'll be able to dilute the oil even further with fresh gasoline.
RAY: And of course he poured it into both tanks. Pouring it into the first tank didn't get the van started (and I'm sure they were late getting to Burning Man for the week), so he tried pouring some in the other tank.
TOM: Diluting the mixture is exactly what you should do. But even if you don't, it won't harm the engine. The oil will burn in the cylinders, so you'll get some bluish-gray smoke coming out the tailpipe --
RAY: -- like every one of the heaps my brother has ever owned.
TOM: Yeah. But in your case, once the oil in the gas tank is gone, the smoke will disappear. And no permanent damage will be done.
RAY: Except to your daughter's social life -- which I'm sure will be severely curtailed from here on in.