Yeah, if the dealer complains about the gas, they’ll have to verify octane by testing it! My lips are sealed.

Just be careful with your trials and if there is a bad result, don’t push your car. Even if totally unrelated, saying you were doing gas experiments if something happens, you don’t want to get blamed!

Thanks for the comments and corrections, folks.

I’m going to try out regular on my car, see how it does, and report back. That will probably not happen for a week or more, though, because I work from home (an even better way to reduce pollution).

If you want to “save money on gas and protect the environment”, get a bicycle. Switching from Premium to Regular isn’t even a drop in the bucket.

Of course, a cleaner burning fuel is more efficient, so less carbon dioxide is output per mile driven – but that isn’t why the EPA encouraged the use of MBTA. In fact, the EPA has refused to regulate carbon dioxide emissions.

Ironically, just this week the Supreme Court ruled that the EPA must regulate carbon dioxide just like all other pollution covered by the Clear Air Act.

Higher octane ratings don’t equate to increased power. Higher octane fuel simply burns slower, making it less likely to explode spontaneously while under compression, thus causing the “knocking” or “pinging” noises you mentioned. In fact, using higher octane fuel than recommended for your vehicle can actually cause decreased performance and leave detergent deposits and carbon buildup in your engine, decreasing performance even further. And of course, this will also decrease your gas mileage. Then again, if you’re looking a way to help burn through money faster (pun definitely intended), be my guest; buy the higher octane.

The short version is this: The Car Talk folks were right. Unless your vehicle is older and you’re hearing the knocking and pinging that indicate uncontrolled combustion, stick to what the manual tells you to use. If your manual isn’t available, contact the manufacturer and ask them directly. They’ll probably need your VIN to identify the make and model (they don’t always want to take your word for it), so have it handy.

Don’t be fooled by the term “grade”. In this case, it doesn’t mean “better”. It means “different”, and has specific uses for specific vehicles. Using the grade that doesn’t match your vehicle is bad for your car, bad for the environment, and bad for your wallet. :-)

Ezra Ekman

If you went into a dark alley and someone jumped out and hit you with a baseball bat fifty times in a minute, that would be bad, right? So, if they offered you an option where they only hit you forty times in a minute, that would be ‘better’, right? wrong. forty beatings in a minute is *still* forty beatings in a minute. ‘Less bad’ is not the same thing as ‘better’.