Did I destroy that gasoline engine by filling the tank with diesel?

Dear Car Talk

Dear Car Talk | Sep 01, 2000

Dear Tom and Ray:

I've been feeling guilty ever since a trip to Italy in 1988. In Sicily, I was buying a candy bar while my travel partner was putting gas in the rental car. When I returned, he said "Boy, I'm not sure what that was, but it sure was cheap, and everybody was using it." The pump was labeled "Gasolio," which I later figured out was No. 2 diesel fuel! Well, that poor little Ford Escort huffed and smoked its way across Sicily, slowing down uphill and just spewing smoke on the down side or on flat ground. We stopped to dilute it with regular gas every quarter tank or so, and eventually it got better. We returned the car to Rome a week and a half later, the rear covered with a thick oil film but seemingly running OK. Tell me, did we do any permanent damage? -- Yours in guilt, Alan

RAY: Did the statute of limitations expire on this yet, Alan? Because I think Interpol is still offering 1,500 lira for your capture (that's a buck and a quarter, Alan).

TOM: I'm actually surprised it ran at all. The ignition point of diesel fuel is much higher than that of gasoline. So if you had a full tank of diesel fuel, it really shouldn't have run at all.

RAY: My guess is that you just topped it off with the diesel and had a good amount of regular gas already in the tank. That plus a high ambient temperature allowed it to run as far as it did.

TOM: But I don't think any permanent damage was done. The '88 Escort in Europe was probably carbureted, so you wouldn't have gummed up the injectors. It probably didn't have a catalytic converter, either, which also would have been ruined by the diesel fuel.

RAY: It's possible to gum up the carburetor, but it sounds like you eventually got it running well, so I think you narrowly escaped without doing any permanent damage, Alan.

TOM: I think you can completely erase this guilt-ridden experience from your mind, Alan. I think we can say with complete confidence that this Escort lived a full and useful rental car life (i.e., about six months).

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