Can You Mix Premium and Regular Gas?

Refueling our car is probably the most important and concerning part of our car. Making a mistake when fueling can lead to serious problems and extreme repair costs. So, with that established, let’s check can you mix premium and regular gas.

What is premium gas?


Just like petrol and diesel, there is a split between premium and regular gas. Both will often be present at the gas pumps, so we’ll get the option to use either. However, what is premium gas?

Let’s explore this question for the sake of a clearer understanding.

What’s different about premium gas?

Premium gas separates itself from regular gas through its octane level. If a type of gasoline has an octane level of 91 or more, it is considered a premium gas. Octane level is a measure of fuel stability. Fuel with high octane level has an easier time withstanding compression before being lit up by the engine. [1]

What’s above premium gas?

Premium gas has an extra distinction based on the octane level it has. For example, the premium gas with an octane level of 91 is standardly referred to as premium, but the gas with an octane level of 93 may be referred to as super-premium.

This additional distinction can be important at some locations, especially if you decide to consistently pour premium gas. The super-premium gas may also be referred to as “ultra-premium” or any other adjective that describes the gas surpassing premium in quality. These refer to the same 93-octane level fuel, even if the names can make it seem different.

Can you mix premium and regular gas?


The answer is yes. Even if there’s a big discrepancy between the octane levels of the fuel, it’s possible to mix them. While the octane level enhances some properties of the fuel, it doesn’t alter any to a degree where it could misbehave in the engine.

As long as you keep proper fuel flowing into the car, petrol for petrol engines and diesel for diesel engines, there won’t be any problems mixing premium and regular gas. As we’ve seen in the example above, the two will simply blend, working as normal within the engine.

Is your car specific in its fuel requirements?


While somewhat rarer, there are engines that will require premium gas. This requirement is usually present in high-performance cars which utilize turbocharged engines. These will usually be luxury cars, and even those with less powerful engines may ask for better fuel. [2]

This requirement is done because the engine needs those additional properties of premium gas. Those being higher resistance to engine knock and extra performance. Without it, it’s tougher to get the most out of the engine.

While newer cars with this prerequisite utilize advanced engines to adjust their operational cycle to any fuel type, the premium gas will still yield the best results.

Benefits of premium gas


Premium gas isn’t just a meaningless increase in price. On the contrary, the extra cost may be justified in some cases due to the sheer benefits of premium gas.

The benefits of premium gas are pretty straightforward.

First, premium gas allows for better utilization of powerful engines. Those who have cars with a decent amount of horsepower may find it harder to accelerate and reach certain speeds as easily with regular fuel. With premium fuel, it becomes much easier to accelerate with those powerful cars smoothly.

On top of that, premium gas can increase fuel efficiency.

The ability to endure compression without lighting on fire means more of it will be burnt for the sake of producing energy. So no matter whether it’s a diesel or petrol engine, it’s possible to see a reduction in fuel use due to it being used better by the engine.

We can also cut down emissions with premium gas.

They run through the engine smoother with their basic advantages and provide us with less emissions.

Of course, all of these assume your engine is made to handle this type of gas. Some engines may not be able to accommodate premium gas, which is something that’ll usually be apparent during first use.

In addition, loud noises and worse emissions due to unburnt fuel may occur, negating the benefits of premium fuel. Check the manual if you aren’t sure whether the engine can accommodate premium fuel. [3]

Related: FSI vs TSI Engines

Why use regular gas?

Price and universality are key selling points of regular gas. A common car will always run on regular gas, while older engines may not utilize premium gas properly.

Regular gas is the lowest in terms of octane grade, coming up at 87. However, that’s also why it’s the cheapest. It can self-ignite during compression, but this can be negligible for some engines.

Is it okay to mix premium gas with regular?

Mixing different types of gas is fine as long as the car’s components are made to do so. When mixed, the octane level of the mix may change and result in a different experience than either fuel used. Let’s check how it functions through an example.

What happens if you mix 93 and 87 gas

While different fuels can’t be mixed, petrol and diesel mix is a death sentence for an engine. What about mixing different qualities of fuel?

The super-premium 93 and the regular 87 are rather far apart in terms of octane grade, which may lead us to question how well they mix together.

The effect of fuel on engine’s operation

Fuel that we pour into our car goes through a four-stroke process whenever we drive our car. These steps include intake, compression, combustion, and exhaust for petrol engines, with diesel ones having slightly modified functions. We’ll stick to petrol ones for the following example.

The fuel is first taken from the tank and delivered to the engine, where it will be forwarded to the compression step. This step is where the octane level of fuel is most important. As we’ve said, the octane level tells us how resistant fuel is to self-ignition during this compression. The more it resists this self-ignition, the more it will provide during the combustion phase. [4]

In the combustion phase, fuel is lit on fire and releases energy while burning. This step gives our engine power which we will get more of with higher octane levels. The exhaust then ejects the gasses remaining.

Can you mix premium and regular gas anytime?

In this situation, mixing premium and regular gas will result in a different octane level for the fuel in general. However, blending the fuel into a mixture that will have an octane level somewhere between the two gas types. Unless you are mixing petrol and diesel, the engine will do just fine with the blend of premium and regular gas.

I accidentally put premium gas in my car

The act of misfuelling can happen to just about anybody. A mistake by the gas pump workers or a slip of the tongue can easily lead to our car being injected with different types of gas than usual. Let’s see how it affects our car when premium gas is accidentally inserted. [5]

Effects of premium gas

Thankfully, accidentally pouring premium gas into your car won’t result in negative effects for it. Premium gas will cost more and may impact your overall fuel efficiency for a bit, but the engine won’t be hampered by it.

It could even be a nice change, offering easier acceleration and fewer exhausts in some cases. Of course, this is all said, assuming you poured the correct fuel type.

Dangers of misfuelling

If you end up pouring the wrong type of fuel into the tank, like petrol instead of diesel, you are in for a completely different experience. Premium or not, engines do not operate well with fuel that doesn’t fit their prerequisites.

Making this misfuelling mistake could heavily damage your engine and cause high repair costs. This is why you should double-check when fueling your car.

Read Next: Can You Mix 5w30 and 5w20


The use of different qualities of fuel is possible. If you mix premium and regular fuel, the engine won’t mind. What will change is the octane levels in premium and regular fuel. While this may affect the general quality of the fuel, it shouldn’t cause any problems.

It’s important to know whether your engine has a specific requirement, though. Premium and regular can both underperform or even damage an engine if it isn’t made to handle that fuel type. Make sure to check manuals and other sources of info if unsure about this.

Other than that, you are good to go. Mixing fuel qualities isn’t something that should be done regularly, but an occasional mix won’t hurt the car. There may be a slight impact on its performance, but nothing noticeable.