Is premium gas worth the premium price?

When you pull up to the pump you typically have three choices: 87, 89, 91 (or 94). But what is the difference between them? And is the benefit for the added expense? And, which one should you be putting into your vehicle?

To start out, let's take a look at what the numbers actually mean. The number on the pump is the octane rating. The octane rating is basically how much the fuel can be compressed in the cylinder before it explodes. The higher the number, the more the fuel can be compressed before it ignites. Higher octane does not enhance the explosion as most people think. It just allows the air/fuel mixture to be compressed to the optimum ratio for that particular engine. Firing at the correct time allows the engine to produce the maximum power it was designed for. 

To better understand compression, let's take a basic look at how an internal combustion engine works. Each cylinder contains an intake valve, an exhaust valve, a spark plug, and a piston. The piston moves down drawing the air/fuel mixture into the cylinder via the intake valve. The piston then moves up compressing the air/fuel mixture. At the moment of peak compression, the spark plug arcs and ignites the compressed air/fuel mixture. The explosion forces the piston down. The piston is then lifted back up and the exhaust is expelled through the exhaust valve.

High-performance engines and sports cars have higher compression engines which benefit from higher octane gas. These engines are designed to compress the air/fuel mixture in the cylinder to a higher ratio than the engines in most cars on the road. This higher compression ratio can mean more horsepower and better performance. If you run a low octane gas in a high compression engine, the fuel will combust (explode) while the piston is still moving up (not at peak compression) causing the engine to knock. If you are running 93 octane gas into an engine designed to run on 87 you will not get any benefits because the engine is not capable of compressing the air/fuel mixture enough. It will not make it any faster, perform better, get better gas mileage, or run cleaner. If your engine is knocking regardless of which octane you put in, you should bring it to our mechanics immediately before your engine requires a potentially expensive repair.

While high-performance sports cars may run best on 93 octane, if that's what they're designed for, most newer engines have sensors that will adjust the timing of the engine to control the knock. It is usually advised in most cases to just use the lowest octane that doesn't cause your engine to knock. Some cases like towing, extreme heat, and performance will require higher octane ratings to maximize engine performance. Again, this only applies to higher compression engines that are designed to run on higher octane fuels. It is best to refer to your owner's manual to see which octane rating is right for your vehicle.

Rather than spending your money on a higher octane gas, you would be better off having your car serviced and maintained to ensure that your engine is performing to it's best ability. At Haus of Cars, we perform all types of engine maintenance to include cleaning a car's fuel system to ensure the injectors delivering the appropriate amount of fuel to each cylinder. Cleaning a car's fuel system can also help restore power. We also have a detail shop offering everything from a simple wash and vacuum to a full 5 stage detail.