Premium Gas



I have a Acura TSX (2005) which uses premium gas. Some friends told me that if I use a lower grade gasoline, the car will adjust to the change not not damage the engine. My wife says that it is silly to risk damaging an expensive car in order to save a few dollars a year. Should I belieive my wife or my friends?

Prentiss Robinson (Anaheim, California)


Your wife is a smart lady.

We’ve had numerous threads on this subject. Seems that lots of folks spend big cash for fancy cars with hot engines and then want to scrimp on gas.

Yes, your car’s system will adjust to prevent pinging, although if you romp on it it may not be able to adjust enough and you may do damage. And the adjustment will cause your car not to perform as well as it did when you test drove it…you know, that nice “hot” feel that caused you to want to buy it in the first place. The explanation has to do with a sensor on your head that senses the shock wave from pinging and retards the timing.

The explanation of the pinging gets technical and has to do with the difference in the detonation of regular vs. premium, higher chamber compression usually due to the gas/air mix being stuffed into the cylinders by a turbocharger or supercharger, compressing matter creating heat, and heat energy being the component that causes combustion. And the preignition thing.

Use premium. And keep the wife. She’s a smart one.


Premium is only recommended in your car not required. You will get reduced performance that may or may not be noticeable to you. I looked at this great car a few years back.

The definitive source is owners manual, words REQUIRED means use premium, RECOMMENDED means for optimal performance and possibly MPG but can use regular.


Wise wife. Great car. Heed wife. Keep both!


Read your owner’s manual. Some cars require premium fuel. Some simply recommend it for increased performance and for use with heavy loads but will allow 87 octane fuel under normal use.

For example, most BMWs require premium fuel. However, my mother’s 2002 Toyota Sienna owner’s manual says premium 93 octane fuel will give better performance but that 87 octane fuel can be used under normal conditions. Since she normally drives it around town unloaded with all of the back seats removed, she has been using 87 octane fuel and hasn’t noticed any pinging or reduction in performance.


Let me add one thing. Using lower octane gas not only means less performance, but it also usually results in less mileage. So you will not save as much as you might think.


I own a car that “requires” 92 octane premium fuel. It seldom gets it. I can detect NO difference in performance or fuel mileage when using 87 octane regular. I have NEVER heard it “ping” or “knock”.

In my opinion, the difference between 87 octane regular and 92 octane premium is not enough to cause engine damage in ANY car. Some cars MIGHT “ping” a little, but that will not cause any damage. Severe detonation, a nasty hammering sound you can not mistake WILL cause engine damage, but I have never heard a modern car engine do that. They just don’t have high enough compression to do that, regardless of fuel used…

Many drivers who purchase premium fuel are making a .20 cent a gallon gift to the oil companies…Very few unleaded cars “need” premium gasoline.


I only noticed with regular fuel my Subaru WRX (high sprung 2.0L turbo engine with 227HP) drops off noticeably in performance since power typically comes on with fury at 3500 RPM(basically very peaky power curve). Also the MPG really suffer enough that the cheaper fuel is offset by lower MPG.