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What do you do when your car only takes leaded gasoline?

Dear Tom and Ray:

I have a 1972 Mercedes 250. It uses regular leaded gasoline, which is getting harder to find at most service stations. When I have to use unleaded gasoline, should I add one of the lead additives that are available in auto parts stores, or should I use a higher octane unleaded gasoline?

RAY: Your's is what we call a lost cause. The leaded gas sold today has just a trace of do the lead additives you mention. The additives, as you've probably noticed, are also very expensive. The purpose of the lead was to protect the valve seats, which get pounded as the engine runs. Rather than fight this, your best bet is to just drive it. If the valve seats ever get destroyed, spend a few hundred bucks and replace them. But you may never have to do it--especially on a car as tough as a Mercedes.

TOM: I noticed that your letter is postmarked from New York City. Another option would be to put some water in your tank. There's probably enough lead in those New York City water pipes to keep this car humming for years.
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