Car terms to know when filling up at the pump

When you’re at the gas station, it may be the price per gallon that catches your attention. But besides knowing the cost of what’s going into your tank, what about the type of gasoline you’re pumping? Here are some car terms to know when filling up at the pump.

Premium vs. regular

The main difference between premium and regular gas is that premium contains a higher amount of octane. Manufacturers have gotten so refined in their engine designs that they specify the appropriate grade of gasoline for each car model. The majority of cars on the market today use the low octane, regular gasoline. Check the automaker’s recommendation for your vehicle in the owner’s manual. As cars age, it may be appropriate to occasionally fill up with a higher-octane fuel, but you should also check your vehicle manufacturer’s advice, or with your mechanic, before doing this.

Octane rating

If you have ever seen a percentage figure on the pump, such as 87, 89, 91, 92 and 93, that number is the octane rating and simply judges the volatility of the gasoline. Regular gasoline is often 87, mid-grade is typically 89, and premium usually 92 or 93. Products with lower percentages of octane burn more easily, and those with higher ratings can help prevent what is known as “engine knock.” Engine knock is when your engine literally starts making a knocking noise, and it’s not a good sign. While most vehicles are suited to octane 87, luxury vehicles may require premium gas with higher levels of octane. But, again, check your owner’s manual.

The Federal Trade Commission advises, “in most cases, using a higher octane gasoline than your owner’s manual recommends offers absolutely no benefit. It won’t make your car perform better, go faster, get better mileage, or run cleaner.”

Ultra-low-sulfur diesel

Perhaps you’ve seen signs for ultra-low-sulfur diesel (ULSD) but wondered what it actually means. ULSD accounts for nearly all the diesel available in the U.S. and burns more cleanly than low-sulfur diesel. It was introduced to meet emission standards for cleaner full.

In addition to the more standard fuel products available, here are some alternatives you may also find at some gas stations.


Biodiesel is a renewable, biodegradable, more eco-friendly fuel type. It can be domestically produced and usually consists of vegetable oil and certain fats or greases. This particular product is friendly to the environment by reducing emissions that normal gas may emit as it burns. Unfortunately, depending on where you live, a fueling station that offers biodiesel may be a little hard to find.


Propane is another eco-friendly alternative to the traditional car fuels. This product blend is probably the most widespread alternative to gasoline. Like biodiesel, it is clean burning and leaves reduced levels of residue in the air. Propane can also offer a high octane rating and high-energy value for an alternative gasoline product.

Become more informed about your vehicle and taking care of it. Read our car terms to know when getting a service, and when getting an oil change.


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