Does Gas Type Really Matter?

There was a mad rush recently to fill gas tanks and canisters in the Northern Virginia area. It was…interesting, but we persevered. Plenty of drivers in the Chantilly, VA area would drive up to the pumps to find the regular or mid-level covered, empty. In the midst of that rush, many drivers were forced to spend more than they normally would on fuel. After all, if you usually put 87 in your tank, but the only option available is 93, what can that driver do? They’ve got to get to work or pick up their family members somehow. So they pay for the premium.

However, does that premium actually have any benefits for a car that doesn’t require it?

That week got our team thinking. We know many drivers are prone to choose a type of gas based on price or the idea of quality but are they aware of how crucial using the proper octane is to their vehicles and their wallets?

If you have ever asked yourself what the numbers on gas pumps stand for, why the gas pump numbers matter, or if gas pump numbers are essential for the health of your car or truck, this blog is for you!


Vehicles with combustion engines contain cylinders and moving pistons connected to crankshafts. Once ignited by the spark plug and expanding combustion gases, it pushes the piston, which rotates the crankshaft.

A cylinder is a chamber where the gasoline is burned and turned into power; it is the central working part of an engine and is the space in which the piston travels. The number of cylinders in a vehicle varies, and most engines have four, six, or eight cylinders. If this sounds familiar, it is most likely because you have at one point or another heard someone say their vehicle has a four-cylinder, V6, or a V8 engine. Those multiple cylinders are commonly arranged side by side in a bank or engine block.


The gasoline found at the pumps is lab-tested by way of comparison with two reference fuels.

One reference fuel is knock-resistant and, when numbered on the resistance scale, has a rating of one hundred (100).

The other reference fuel knocks easily, and its rating is zero (0).

Octane numbers determine the likelihood of knocking within an engine.

The two fuels are combined to make the reference fuels used as a basis of comparison for the gas you are buying at the pump.

As fuel arrives at the lab for testing, it gets compared to the reference fuels. When a fuel acts as a comparison mixture (reference fuel) with 87% knock-resistant fuel, it gets labeled with an octane number of 87. The same goes for 88-90 and 91-94. In other words, the higher the octane number, the more resistant it will be to causing a knock.


While knocking depends partly on the engine’s compression ratio, some engines require higher octanes to avoid as much. If you have been using a lower octane on your vehicle without hearing your engine knock, there probably is no need to spend more money at the pump than necessary since the high octane doesn’t provide much of a benefit. However, we always recommend that you refer to the manufacturer’s manual, where you will find the octane best-suited for your vehicle’s engine.


Above all else, pay attention to your vehicle. Take notes of every sound, scent, and noise you might notice for reference when visiting your automotive shop. If you suspect you hear your engine knocking, come on by Casey’s Automotive. Our teams of certified technicians in Chantilly, VA, can service your automotive needs. Contact us to make an appointment.

The best referral you can get is from a neighbor.