Gas Saving Tip #4
[ July 24th, 2008 ] By: Charles Smith Posted in » Tips and Tricks
While this is not so much a gas saving tip as it is a money saving tip, I think it addresses a common misconception about gasoline.
Stick to Low Octane Gas. If you don’t have a requirement for above 89, buy the lowest octane gas that will keep your car working. Octane has nothing to do with engine performance by itself. That is 93 octane will not make a car that only needs 87 octane run better.
Higher octane gas can put up with higher temperatures before it ignites, so high performance engines take advantage of this fact. They compress and heat up the gas and air more than a normal engine would in various ways. They could turbo/supercharge, increase compression in the cylinders, etc… All of those would require higher octane gas. If they used lower octane gas, the engine may start to knock. That means the gas is igniting before the spark and you can damage many parts of your engine when this happens.
So unless your engine requires it to prevent knocking (detonation), stick to the lower octanes.
July 24th, 2008 at 7:56 pm
I’ve found that it varies a lot with how I drive. The ECU will pull back ignition timing to prevent knocking when I push the engine a bit. So with the way that I drive, I’ll usually see 1-2mpg better fuel economy with 93 over 87.
It was a long time ago that I checked, but last time I ran 87, I found that for that particular tank compared to my usual mileage with 93, the 87 was more expensive. Of course, this varies with every car, how you drive, the weather, etc. :P