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Fuel Options Demystified

When pulling up to the pump there are several fuel options for your vehicle. What’s the difference? Which is right for you?


Unleaded Gasoline

Most vehicles on the road run on unleaded gasoline. Most gas stations offer three options for unleaded gas: Regular, Midgrade, and Premium. The difference between these is the octane level. Octane works with your engine in a variety of ways to make your car go. Generally speaking, the higher the octane level, the better engine efficiency and performance


Regular Gasoline

Regular gasoline tends to have the lowest octane levels. The minimum octane levels by law in the US varies from state to state. Most states require that regular unleaded gas have a minimum octane rating of 87, but in some states it’s as low as 85. 


Midgrade Gasoline

Midgrade, as the name suggests, has octane levels somewhere between regular and premium gas. It’s often just a blend of regular and premium. Not only do octane levels for midgrade vary from state to state, but also from gas station to gas station. Octane levels range from a rating of 87-89 with 89 being the most common in the United States.


Premium Gasoline

Some luxury and sport vehicles require premium gas like Audi, Cadillac, and Lexus. That’s not to say all models in those brands do. Often cars with turbo engines and direct-fuel injection systems require premium. However, more and more standard vehicle brands are manufacturing premium gas only vehicles. Chevy, Jeep, Subaru, Toyota, and Volkswagen are just a few manufacturers with models that are requiring premium. 


Leaded Gasoline

If we use unleaded gasoline, is there leaded gasoline? In short, yes, but we don’t really use it anymore. In the 1920s the US started using lead as an additive in gasoline to reduce engine knock which increased the engine efficiency and performance at the time. Due to the devastating health effects caused by toxic leaded gasoline, the US passed a law that required vehicles made in 1975 and later needed to run on unleaded gasoline. It wasn’t until 2021 that use of leaded gasoline for on road vehicles was banned globally. However, leaded gasoline is still used today in some aircrafts, marine engines, race cars, and farm equipment. 



Diesel fuel is thick compared to gasoline. Less fuel is needed to run a diesel engine. They are big, heavy-duty power machines that are more simplistic in design compared to the precision engineering in their gasoline counterparts. Although diesel fuel has the consistency of a light oil, it becomes thinner as it heats up. The benefit of this is that diesel fuel also lubricates and can reduce overall wear and tear on the engine. At the pump, diesel fuel tends to cost more per gallon than regular gasoline. The octane rating for diesel tends to be between 25-40. Diesel fuel is not compatible with gasoline engines nor gasoline in diesel engines.


Off-Road Diesel

As the name suggests, off-road diesel is intended for use in vehicles such as tractors, construction equipment and some generators. Because it isn’t used for on-road vehicles, there is no tax for this fuel. However, it is illegal to use this fuel for on-road vehicles. A dye is added to the fuel to easily test whether it’s being used illegally, and misuse can lead to a hefty fine. 



Also known as Flex Fuel, E85 is considered an alternative fuel available for some vehicles. It is a blend of somewhere between 85% ethanol mixed with 15% gasoline. As ethanol is created from corn, it can be easily supplied in the US. The idea behind creating this alternative fuel blend was to reduce dependence on foreign oil and it creates less pollution so there’s less impact on the environment. While E85 will have a lower price per gallon than regular gasoline, drivers will notice they’ll get fewer miles per gallon. It’s important to note that E85 can only be used in vehicles designed to utilize the alternative fuel. E15 and E10 also exist, and if you’re purchasing regular gasoline at the pump, chances are it’s actually E10.



Rec-90 is an ethanol-free fuel with an octane rating of 90. It is most often used in marine vehicles and aircrafts that are not designed to be used with ethanol which could cause severe damage to the engine. Many people prefer to use rec-90 in lawnmowers, chainsaws, and snow blowers. The jury’s still out on whether there is any benefit of using rec-90 fuel instead of regular gasoline for on-road vehicles. Rec-90 fuel is only available at select gas stations. 


Which Fuel to Use?

With so many options available at the pump, it may be difficult to know which type of fuel is right for your vehicle. Always consult the owner’s manual to determine which fuel is best suited for your vehicle. 

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