2003 Lincoln LS: Do I Have to Use Premium Gas?

Q--I have a 2003 Lincoln LS that is mainly used for occasional vacation trips and some drives around town. My owner's guide recommends using gas with an "octane rating of 91 or higher for optimum performance." (Why do they say to use 91 octane when most gas pumps have 87, 89, and 93 octane? Does octane vary by region?)

A friend with the same model and year uses only regular gas (87 octane). I'm planning a trip to visit friends in Virginia and with the high prices of gas, I was wondering if I could use 87 or 89 octane without damage to my engine? I don't wish to be pennywise and pound foolish.

A--Unless you need "optimum performance" all the time, feel free to use regular or mid-grade gas. But I would suggest switching to the premium fuel when driving in the mountains as your engine may ping climbing some of the grades and pinging can cause engine damage.

Yes, octane does vary by region. In the Rockies and the high plains, you will find 91 octane premium at the pump. I have no idea if the bourbon there is only 78 proof, though.