There is a common misconception that the more expensive gasoline is, the better it is. Many people pay the few extra dollars for premium gasoline (Octane 91 or above), thinking that they are doing the best thing for their vehicles. In reality, nothing could be further from the truth. In the same way your vehicle uses a particular grade of engine oil, it also uses a particular grade of gasoline. The fact that gas stations offer you the option of any grade doesn’t mean that you should assume the higher the better. In fact, you could actually be doing more damage to your vehicle than you think. Knowing which rating of gasoline your vehicle requires is just as important as knowing which engine oil, transmission fluid, or coolant it takes.

I Was Always Taught Bigger is Better, What Gives?

A higher octane fuel has nothing to do with power. Contrary to popular belief, it also has nothing to do with the internal cleanliness of your engine. Lower octane fuel is designed to burn easier. This makes it the ideal fuel for most of the vehicles on the road today. The higher octane is used mostly for higher performance vehicles. This has to do with a little thing called “engine ping” or “knock.” Basically, this is referring to a detonation within your engine’s cylinders, which wasn’t initiated by a spark from the spark plug. Since higher performance vehicles run at higher temperatures, a lower grade fuel will run a greater risk of detonation absent of spark. Higher octane fuels are designed to burn slower than regular. That’s where the problem comes in for regular vehicles. Using a gasoline that is designed not to burn as easily, like premium, can increase the chance that your vehicle isn’t burning all its fuel, making it less efficient and causing a greater risk of having parts fail.

Can it Really Damage Other Things?

In a word, yes. Not only will it decrease your fuel efficiency, if you’re not burning all the fuel within the engine’s cylinders then it’s being pumped out through your exhaust and past several of your vehicle’s emissions system parts. This can burn out oxygen sensors, plug up catalytic converters, and cause backfires which can be noisy and dangerous. Granted, you probably won’t notice any of these things after your first few tanks; so if you’ve been using the wrong grade for a little while, don’t panic. However, you may want to take your vehicle to a repair facility and just have it inspected to be sure. Just be certain to tell the technician exactly why you’re there so he/she will know the right places to look, and what parts to check.

So Which Gas Should I Be Using in My Vehicle?

As with all other information about your vehicle, this can be found in your owner’s manual. Most vehicles, aside from the high performance beasts, will require the standard grade (Octane 87 in the U.S.). If you don’t happen to have your vehicle owner’s manual, there are still plenty of resources available where you can find the information. Your local vehicle dealership would be the best place, but there’s always the old, reliable Internet as well.

I Thought Premium Gas Was Cleaning Out My Car, What Now?

If you’ve found out that your vehicle takes grade 87, but you’ve been using premium in the hopes that it was cleaning the carbon deposits from your engine, don’t worry, all is not lost. While you probably haven’t been doing much to prevent the carbon deposits by using the wrong gas, that doesn’t mean there aren’t products out there that can do the job well. Take a run up to your nearest trusted auto parts store and ask for the best carbon cleaner they have. Just make sure you take your vehicle in for a tune-up right afterwards, especially if you’ve been using the wrong gasoline. The release of all that built up carbon could cause some problems if it’s not thoroughly cleaned out.

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