How to Figure Out the Proper Grade of Gas

There are a lot of misunderstandings in regards to fuel grades – and by fuel grades our auto mechanic experts mean the octane rating. With names like “Standard”, “Super”, “Plus”, and “Premium” it’s easy to see why you might associate the octane rating/grade with quality. Octane ratings are shown as a number that usually ranges from 87 to 91 at the pump. The number does not mean “better” but rather signifies the appropriate amount of a certain grade of fuel for a certain engine.

How It Works

Octane is a measure of gasoline’s ability to resist igniting before the spark plug goes off. Gasoline and air compress in the engine’s combustion chamber. When that pressure reaches a certain point, the gas will spontaneously combust. You don’t want that happening; rather, you want the spark plug to ignite the fuel at the exact right time. When the gas combusts too soon, the piston will try to lower while it is still being pushed up by the crank shaft and that is when you hear a pinging or knocking sound. That sound is metal knocking into other metal when it’s not supposed to. Our auto repair experts know that this can lead to expensive damage.

Because engines have different designs, they also have different compression ratios. An engine with a higher compression ratio needs gasoline with a higher octane rating to stop combustion occurring to soon. Also, turbocharged or supercharged engines have higher pressure in the engine and will usually require higher octane gas. To sum it up, your vehicle has a recommended octane rating – which is usually found on a sticker in the gas cap area – and you should always use at least the recommended octane number. Using a lower octane rating than what is recommended could lead to engine damage. Using a higher octane rating than recommended will not have any visible power or efficiency benefits in most of the new engines we see today.

Quality of Your Gasoline

Now, just because the octane number doesn’t measure quality, that doesn’t mean there isn’t a difference in the quality of gasoline. The government mandates that all gas have a minimum level of detergent added to keep the engine and critical fuel system and emission components clean and running efficiently over a long period of time. Top tier gasoline will have higher amounts of detergent than the recommended minimum. To express to you how important this is, all U.S. car makers use top tier gasoline in their government mandated 100,000 mile durability tests. At our North Olmsted auto repair shop, we know good quality fuel is critical to the long life of engine components.

Whatever gasoline you may be using, there will be some carbon build up on your valves, pistons, fuel injectors, etc. This is especially common on the intake valves of the GDI (gasoline direct injection) engines that are found in more and more vehicles we see at our auto repair shop because the gas is injected directly into the combustion chamber and the detergents in the fuel do not get a chance to wash over the intake valves. A professional fuel system cleaning is needed to clean and restore the efficiency of your fuel system and keeping fuel economy up. Our auto mechanics can make sure your vehicles fuel system is performing at top level.

Stop by our North Olmsted auto repair shop for a professional fuel system cleaning.