Reader Question: Octane and Altitude?

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Here’s the latest reader question, along with my reply!

Robert asks: Why is the high(er) octane fuel being sold at this altitude? It’s not necessary. Ignorance is bliss? We sure enjoy your writing and subject matter and outlook!

My reply: Because some cars still need high-octane fuel!

However, “premium” (high octane) gas in high altitude areas often has a lower octane rating than “premium” sold in low-altitude areas.

This is because at higher altitudes – such as Colorado – thinner air compensates for lower octane than an engine needing “premium” would otherwise need for optimum performance/efficiency at lower altitudes.

However, this doesn’t mean you should use a fuel with an octane rating different than that recommended by the manufacturer of you car.

And regardless, the car’s computer will adjust various parameters such as spark timing to compensate for lower-than-recommended octane fuel – so you won’t hurt anything if you use less-than-optimum (for your particular engine) fuel, though you may notice a dip in fuel economy and performance.

. . .

Got a question about cars – or anything else? Click on the “ask Eric” link and send ’em in!

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