Topping off the tank can be costly

January 30, 2009

Dear Tom and Ray: I got into an argument recently concerning whether I should top off when I fuel up. You know what I mean -- the pump shuts off, and I can either stop of put another half a gallon more in. Is that OK, or not? I notice some pumps say not to top off, and I was wondering why. Most reasons I have found online discuss fuel expansion, which, it seems to me, would be rather minimal. So now I am asking the experts . . . can you point me in the right direction? -- Kurt

RAY: Was the "argument" with a spouse, by any chance, Kurt? Who else would you ever get into an argument with at a gas station? Anyway, you owe her an apology, Kurt.

TOM: Vaporization is the problem. In the old days, gas caps used to have holes in them so gasoline vapors could escape. The vapors went right into the atmosphere, creating smog and preventing Sarah Palin from seeing Russia from her home in Alaska. Oh, and the other problem with smog: lung disease.


RAY: To solve the problem, the Environmental Protection Agency required that all cars come with a vapor recovery system. A key piece of that system is something called a charcoal canister, which is attached to the gas tank.

TOM: When the gasoline in the tank expands and creates vapors, those vapors are absorbed by the charcoal. They're held there in the charcoal until the next time the car starts, and then the vapors are sucked back into the intake air, and burned by the engine during the combustion process.

RAY: When you top off your tank, you take the chance that you'll force liquid gasoline into the charcoal canister, ruining it. And what does that mean? At least 300 bucks, Kurt.

Dear Tom and Ray: My rich old auntie recently shed this mortal coil and left a 1996 Toyota Camry Collector's Edition with only 14,000 miles. Other than making only spotty trips to the liquor store, the car has not been used for the past two years. It is a luxurious car, to be sure, but would I be asking for trouble because of its inactivity? -- Annie

TOM: Gee, when my aunt died, all I got was a set of gas-station dinner plates. You, on the other hand, have struck pay dirt, Annie.

RAY: This is an excellent car, and we see many of them in the shop with 150,000 or more miles on them still going strong. So I think you'd do very well to weasel it away from any other covetous siblings who are eyeing it, and pounce.

TOM: If the car's been used occasionally the past two years, that means it runs, which is great. So there's no concern about internal engine parts sticking or rusting together.

RAY: Unlike, say, your heart muscle, engines don't weaken when they sit around. In fact, the less they're used, the longer they last. My brother's got a bunch of old cars. The only reason they still run is that most of the time he can't get them started.

TOM: The only parts that DO wear out over time, even if you don't use them, are rubber parts. Rubber is broken down by ozone in the air. So, even though the tires have only 14,000 miles on them, they've been deteriorating for a dozen years now and should be replaced. The same is true for the belts and hoses, including the timing belt.

RAY: But for $1,000 or so, you can get all new tires, belts and hoses, and have, essentially, a brand-new car that'll last you for many, many years. And for an extra $50, we'll call your siblings and assure them that it's junk.

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