Saving Money on Fuel: Do You Really Need to Use Premium Gas?

When drivers pull into gas stations, one of the first things they look at is the gas price for the day. This number is so important that many will travel miles away to save a couple cents per gallon.  With that kind of thrift-driven motivation at play, a natural thought for most people is “Do I absolutely have to use high octane gas? It’s more expensive than regular!” It is really an issue for automobile owners.Read this article to find out about premium gas, and when you may or may not need to use it!


When to use premium

There are occasions when you may want to use premium gas despite the fact that you don’t need to. For instance, if you are driving through the Arizona desert, its 120 degrees out and you are towing a trailer. In this type of situation, your vehicle’s powerplant will be ingesting very hot, dry air, and this combination can lead to spark knock.  In a case like this, higher octane fuel would help out.


When mistakes occur

If your vehicle needs premium fuel and you put regular in your tank, it’s not a big deal.  In the old days, this could have been an issue when driving when it’s hot outside but not so much in the modern day. Most automakers have robust enough engine computers that they will compensate and nothing serious would happen. The computer will alternate the spark timing and running a rich air-fuel mixture to compensate for it. Next time you fill up just be sure to use the correct octane gas.


What’s octane?

Octane is a measure of gasoline’s resistance to igniting under pressure. But, what does that mean?  Why is a gasoline’s octane rating super important?  It ties into “compression ratios.” To improve the power of their engines, manufacturers usually increase the compression ratios (how tightly they squeeze the incoming air-fuel mix) in the engines. A high octane fuel may be squeezed tighter in the cylinder before it ignites, which means that high-performance engines usually need higher octane fuels.  Otherwise they’ll experience something called “pre-ignition.”

Using a low-octane fuel

If you fill your vehicle with gasoline of the octane grade that is manufacturer-recommended, everything will be OK.  But what happens when you use a lower octane fuel than what the manufacturer says to use? What may happen is a phenomenon called “spark knock”.  It’s like a high-pitched pinging, or perhaps a rattling noise from the engine. The sound is caused by colliding flame fronts inside the combustion chamber, which leads to pressure pulses to ultimately make that sound.

Is this an issue?

Yes! It can cause internal engine damage.  If an engine is allowed to knock long enough, such as on a hot day pulling a trailer, you could melt holes in the pistons.  Fortunately, a disaster of this level unlikely in today’s highly tuned, computer-controlled engines but you still do not want spark knock happening in your engine.

Thank you to the amazing Service Team at this Roswell, GA Dodge dealership for their help with this article!

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