How To Know If Your Vehicle Requires Premium Gas

If you’ve spent any time at a gas pump, then you’re likely familiar with the “Regular”, “Plus”, and “Premium” options, as well as the numbers displayed on each button. While the names seem to imply these refer to the quality of each gasoline mix, this is more of a misconception and some clever marketing tricks at work.

In this article, we’ll go over what the names and numbers really mean, how they affect your engine, and how to know which one to be pumping into your own vehicle.

Octane Explained

Although the specific numbers vary by region and gas station, each of the three options refers to the octane number of the gasoline. You’ll commonly see octane ratings such as 87, 91, and 93 listed across the three individual buttons. While many drivers simply assume “higher = better”, there’s more to this equation than the names and numbers alone would let on. 

Octane is the ability of the fuel to withstand premature detonation of the fuel, also known as knock. This may sound like a good thing to pay a little extra for, and for some vehicles it is, but the important thing to know is that higher knock-resistance only matters in engines with high-compression ratios. 

Compression Ratio

Compression ratio is the ratio of the cylinder’s volume while the piston is retracted versus that of while it’s extended. A higher compression engine means you can extract more power from the air-fuel mix, which is why higher compression engines are more commonly seen in performance and luxury vehicles that push their powertrain to the limit of available power.

Higher compression comes with some very real practical tradeoffs though, such as the tendency of fuel to pre-detonate at high compression. Higher octane fuels are able to withstand this extra compression, which is why Plus or Premium gasoline is recommended for these vehicles by the manufacturer. 

In vehicles without a high-compression motor, you’ll see little to no actual benefit in filling up with the more expensive options at the pump, as high-octane fuels only matter in engines that require them to prevent knock.

How Does Pre-Detonation Affect My Engine?

If an engine is high-compression and is run on lower octane fuel, it will likely knock at some point. This can be extremely harmful for the engine, as the premature detonation can cause internal components of the engine to collide as a result of the early combustion.

A knocking engine as a result of improper fuel may sound like a pinging or rattling noise. If you notice this from your own motor, it’s crucial to have it inspected as soon as possible to avoid irreparable engine damage. 

So Which One Do I Need?

The majority of vehicles on the road don’t require higher octane fuels, and likely won’t see any upsides in doing so. However, no matter what you’re driving, it’s always important to check the recommended octane fuel for your vehicle.

This information is easily obtainable in the owner’s manual, and is often listed on the back of the gas lid itself, meaning it only takes a few seconds to ensure you’re not putting your engine at risk. 

Fuel System & Engine Services in Tucson, AZ

If you’re experiencing unusual sounds or feelings from your engine, don’t hesitate to reach out to the friendly team at Micro Import Service in Tucson! Our team has extensive experience in inspecting, diagnosing, and repairing the engines and fueling systems of various import makes and models. Give us a call or schedule online today to secure your appointment!