Sacramento Area Miata Owners Association

Fuel Tips from Grassroots Motorsports Magazine

Presented by Sunoco Fuels

This article is in the current copy of Grassroots Motorsports and I feel it answers the question that has been asked many times...Am I wasting money by filling up with more expensive higher octane gas...?...The answer according to this article is, it depends...But the answer according to Sunoco Fuels expert, Zachary Santner is probably yes.

"If the owner's manual calls for 87 or 89 octane gasoline, are you wasting your money filling up the tank with 93 (or in California, 91)?  As with most things in life, it depends...

What is octane?  Search for the term "high octane" and you'll finds all kinds of results: highd-octane workout,high-octane coffee, and even high-octane fishing charters.

"The word octane is sold as power," notes Zachary Santner, technical specialist with Sunoco, "which is ironic because the word octance has nothing to do with that".

Octane doe not measure energy content, he continues.  Octane is a measurement of resistance to autoignition-also know as pre-ignition, pinging or knock.

The take-home message here: If an engine isnt't knocking with a lover-grade fuel, a higher-octane fuel isnt't to going provide any performance advantage.  (Modern engines can automatically retune themselves when encountering pre-ignition, meaning you likely won't hear it, so Santner recommends simply consulting the owner's manual regarding a cars octane requirements-assuming of course, that things under the hood are still stock."