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Enhanced gas claims mostly hot air

Boston Herald

By Tom & Ray Magliozzi / Car Talk
Sunday, July 12, 2009

Dear Tom & Ray:

Is there any merit to the claim that nitrogen in gasoline helps clean a car’s engine, or is this just the latest gas-additive scam?

What’s the chemistry behind this claim?

– David

RAY: We assume you’re asking about Shell Oil’s latest ad campaign, which calls the company’s gasoline “nitrogen enhanced.” Well, like most of the “enhancement offers” that come via e-mail these days, this one should probably be ignored, David.

TOM: Shell purports that its new “nitrogen-enhanced” gas keeps your car’s engine cleaner.

RAY: But all gas must by law contain certain additives that help block deposits from forming on your car’s valves and other engine components. All of these additives contain small amounts of nitrogen.

TOM: However, nitrogen is only one of several ingredients in these cleaning additives. So our guess is that Shell increased the amount of cleaning additive in its gasoline, “enhancing” the nitrogen component.

RAY: And more cleaning additive is good, right? After all, they put in such small amounts of nitrogen that a little extra won’t affect the amount of nitrous oxides that come out of your car’s tailpipe. And if your engine runs cleaner, that’s all the better.

TOM: But what the claim “nitrogen enhanced” doesn’t tell you is how much additive the gas had in the first place. Did Shell previously add the absolute minimum of additives to its fuels? There’s no way to know, because that’s a trade secret. By claiming its gasoline is “nitrogen enhanced,” all Shell is saying is that its gas now has more nitrogen in it than before.

RAY: Right. It would be like me and my brother claiming that our column is now “enhanced with right answers.” That could mean that we’re putting more time into answering each question – or just that we’ve enhanced the column to the point where we now get at least one answer right per year!

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