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Q: A friend has a Prius that he has driven for about 18 months and still hasn't used up the original tank of gas. How long will this gas last? Is there any danger that because he uses the gasoline engine so rarely, that it might not fire up when he needs it?

A: Over time, gas loses some of its components. Gasoline contains alkanes, alkenes and naphthenes. These light hydrocarbons eventually evaporate, causing "stale" gas. If your friend is going to nurse his gas for such long periods, a fuel stabilizer such as Sta-Bil or Sea Foam can help it last. As for the engine failing to fire, there is little danger of that.

Open and shut case

Q: My last few cars have had a quick-touch window button — you touch it once and the window goes all the way up or down. Is there a way to change them to work how you want them to?

A: When you say "work how you want them to," I presume you mean the ability to open the window just part way instead of full up or full down. You don't mention what kind of car you have, but on most models, if you hold the button down (rather than just give it a quick press), the window will stop moving when you release it. It might take some practice with the timing to get it to stop where you want, but it's a lot easier than retrofitting your car with hand cranks.

A sticky question

Q: I've heard that magnetic oil drain plugs remove small metal stuff that the oil filter misses. Do you think that one of these plugs could enhance and prolong a trouble-free engine life?

A: I like magnetic drain plugs, but not because they trap stuff that the oil filter won't. The filter will, indeed, trap the stuff. Particles on the drain plug provide a hint to wear: no particles, no excessive wear. Remember, though, that magnets only attract ferrous (iron) particles, not anything else.

Tired tires?

Q: A car dealer is advertising "buy three, get one free" tires. While researching the tires that were on sale, I discovered that the model has been discontinued for more than a year. The dealer is offering road hazard service in the package. But should I be concerned that the tires have been sitting in warehouses for so long?

On a related matter, if I bought tires at Walmart, could I go to a dealer for alignment?

A: Tires sitting in a warehouse do not really age, and I would have no problem buying tires that are well past their manufacturing date. You don't encounter this more often because high-volume tire sellers seldom have such old stock hanging around. Most manufacturers will honor the hazard warranties on their discontinued lines. As for your second question, buy your tires wherever you wish and get your alignment wherever you wish.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to