Why does my car need premium gas? | News


Premium gas has a higher octane rating than regular gas. The octane rating is a measurement of a gasoline’s ability to withstand problems such as engine damage and humming knocks, which can be caused by the high pressure, turbocharging or supercharging typically used in high-performance engines. It can also be caused by carbon deposits in old engines.


Related: Mix regular gas with premium to save money at the pump

The question about using premium gas usually arises because people have seen a note inside their car’s fuel door indicating premium fuel. However, in terms of having to use premium fuel in newer cars, the phrase “premium fuel recommended” has a different meaning than “premium fuel required” or “unleaded fuel only.” (Some may list a lower octane rating.) If the label says, “Premium Fuel Recommended,” you should be able to use regular gas safely. But if it says “required” or “only”, you should use the premium version.

Higher compression in the engine produces higher horsepower, but it may require premium gas to do so. That’s because newer engines have electronic knock sensors that can detect the start of a knock and hum and tell the computer to back off the engine’s ignition timing to compensate for low-octane fuel, although power may drop slightly as a result. On turbocharged or supercharged engines, the boost (which produces more horsepower, but may require premium fuel to do so) can also be rolled back to do the same.

For example, for the 2022 CX-5, Mazda lists its turbocharged 2.5-liter engine as producing 227 hp on regular fuel and 256 hp on 93 octane premium fuel. In this case, simply premium gas is recommended (some fuel door codes may add “for best performance”). So, if the sign inside the fuel door says, “Premium fuel recommended,” it’s okay to use the regular system. You may not get the same amount of power.

What if I accidentally fill up my closet on a regular basis when a premium is needed?

If you accidentally put regular gas in a car that requires a premium, you should be fine, although there are things you should probably do to help compensate. There will likely be some installment left in the tank that should help make up for the usual you put in, but you can improve your odds by driving gently and filling the tank with the installment when the tank drops to three-quarters full – and then again half-full.

Exception in older engines

Regardless of the recommended fuel, drivers of older cars may notice some knocks and hums coming from the engine, especially when accelerating. Sometimes this is due to carbon deposits that have accumulated in the cylinders, which can not only effectively raise the compression ratio, but may also develop into hot spots that can prematurely ignite the fuel-air mixture. In some cases, using a high-octane fuel is enough to reduce or even eliminate knocks and ping. If that doesn’t help, it’s time to see a mechanic.

bottom line

If you don’t notice a knocking or humming noise coming from your engine, and if premium fuel is only recommended for your car, you should be able to use regular fuel without problems. But if premium fuel is needed, it is definitely better to fill it with an additional fee.

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