Arizona Gasoline Types Explained

Arizona Gasoline Types Explained

Chris McCurdy explains gasoline types and related automotive effects.

Arizona Gasoline Types Explained
Experienced Arizona auto mechanic, Chris McCurdy, explains how different gasoline types affect fuel efficiency and auto performance.

Gas prices are dropping in Arizona, as they are throughout the country. This week, the average price for a gallon of regular unleaded gasoline was $2.05. Gas prices are expected to continue to stay low through at least the first quarter of 2015. Fluctuations in supply have a major impact on prices at the pump, so it’s hard to predict long-term costs with any certainty.

Now that prices are lower, drivers might be tempted to spring for higher grades of fuel. It is important to understand what makes each fuel type different to make the best choice for your vehicle. Of course, you must fill your tank with whatever gas type your manual says. However, if you have flexibility, choosing a higher grade may be helpful.

Here’s what you need to know:

Regular Unleaded

There are three grades of unleaded gasoline: Regular, mid-grade and premium. These are common names for gas that is actually rated by its octane level. Regular unleaded gas has an octane rating of 87.

Octane ratings refer to gasoline’s ability to withstand compression. The higher the number, the more pressure it can withstand before it ignites. When fuel explodes instead of burning in a controlled manner, it can create a knocking in the engine.

Regular unleaded gas has the lowest octane and, therefore, can withstand the least amount of compression. It is acceptable for use in most standard automobiles, but would not be suitable for high-performance vehicles.

Regular unleaded gas is also the least refined type of unleaded gas. It has more contaminants, which some believe can reduce fuel efficiency and longevity.

Meet Fred McCurdy Professional AZ Mechanic at Scottsdale Muffler & Automotive

Mid-Grade Unleaded

Mid-grade fuel has an octane rating of 89. Most vehicles will either require unleaded gas or premium unleaded gas. No cars state that they must use mid-grade gasoline specifically. In fact, many drivers either use regular unleaded gas or skip straight to premium.

Mid-grade fuel offers an option for those who want to get higher performance from their engine but don’t want to pay as much as premium.

Premium Unleaded

Premium unleaded gas has an octane rating of 91 or 93. Premium unleaded gas is usually required by high-performance vehicles, such as sports cars. Those whose vehicles that do not require premium unleaded gas may still use it in order to maximize the potential of their engine. Premium gas is also better for cars driving in extreme heat (common for Arizona summers) and for those towing a lot of weight.

Premium gas also has the fewest contaminants, so using it can help with fuel efficiency.


In engines that use unleaded gas, a spark plug is used to ignite the fuel. Diesel fuel automatically ignites when it is subject to very high pressures. Diesel is not measured by an octane rating, but rather a cetane index and number.

Diesel fuel is not an optional fuel. An engine must be designed specifically to use diesel fuel because of the way it is behaves. Therefore, diesel engines cannot use regular fuel, and cars designed for regular fuel cannot use diesel.

Historically, diesel was a cheaper fuel than unleaded gas. However, it has recently become much more expensive than unleaded gas.

Tempe Arizona Auto Repair Specialists at Scottsdale Muffler and Automotive

Choosing the right kind of fuel will make a big impact on your engine’s performance and the life of your car. However, choosing the right fuel additives and having an Arizona mechanic perform regular maintenance for your fuel line and engine are also extremely important. Scottsdale Muffler and Automotive can help you understand the maintenance service that your car needs and recommend the right schedule for it. We can recommend the right fuel additives and explain how different grades of fuel will affect your car’s engine specifically. Call us today to schedule the maintenance that your car needs.

Published By

Scottsdale Muffler & Automotive
1710 E Curry Rd
Tempe, AZ 85281

Office: 480-994-4741

Office Hours:
Monday: 8:00 a.m. – 5:00 p.m.
Tuesday: 8:00 a.m. – 5:00 p.m.
Wednesday: 8:00 a.m. – 5:00 p.m.
Thursday: 8:00 a.m. – 5:00 p.m.
Friday: 8:00 a.m. – 5:00 p.m.

Posted: February 20, 2015