What Type of Gas is Best for My Car?
When you pull up to your nearest gas pump to fill up your car, truck, or SUV, you’ll likely see a few different types of gas available. Sometimes it might even seem like too many choices! Regular, premium, high-octane, E85, E15, ethanol-free and more all make their appearances on pumps. That’s not even including the diesel and kerosene pumps – although if your vehicle runs on those, you surely already know what to put in.
So what are these different types of fuel, and which type is best for your car, truck, or SUV?
The Ethanol Question
In the pursuit of fuel that is more renewable than what we pump from the ground, the addition of ethanol has become common. In eleven U.S. states, E10 – a blend of 90% gasoline and 10% ethanol – is mandatory for all road-going cars. In many states, the gas you’re pumping will be E10 as well, it’s just not mandatory for every fuel to be E10 or better in those states. You can still find ethanol-free fuel, but it is rare and regularly found in rural communities – it’s the better choice for lawn equipment.
While almost every consumer vehicle can burn E10, it’s not necessarily true for higher blends. E15 and E25 blends are available and can be used in specific vehicles. E15 blends can be used in most vehicles made after 2001. E25 fuels can be used in a number of BMW and Mini cars and SUVs. Check with your owners’ manual to see if any of these fuels should be used or avoided!
On the other end of the spectrum, E85 fuel contains 85% ethanol, and is specifically for use in Flex-Fuel vehicles. If your vehicle is not labeled as being Flex-Fuel, FFV, or E85 Ready on the badge or in the owner’s manual, you won’t want to use this.
The octane rating of a gasoline indicates the fuel’s ability to withstand compression in an engine without detonating. A higher number indicates the fuel can withstand greater compression before detonating.
Why does this matter?
Internal combustion engines require a mixture of air and fuel to be compressed together. That is then ignited by electric spark plugs. A higher-octane fuel can withstand greater compression than a lower octane fuel. A lower octane fuel cannot – and when it is used in a high-compression engine found in high-performance vehicles, the fuel may ignite before the peak of the combustion cycle in the engine. This produces engine knock, which can range from annoying to potentially destructive in an engine.
A higher octane DOES NOT mean greater power output. That’s a misconception, driven by the fact that many high-performance engines require high octane ratings. In this case, those high octane ratings are required because the engine requires higher compression for greater power, not in order to provide that extra power.
Higher octane also DOES NOT mean it burns cleaner or more thoroughly. That is an old wives’ tale that has been kicked around for years, but it’s untrue. Again, it’s the engine itself that is the factor here, not the octane – many higher compression engines simply do a better job.
Octane is not measured on a scale of 1-100 either, as you may see numbers above 100 in some countries. In fact, E85 – mentioned above – generally has an octane range of 102-105!
Which Octane is Best for My Car?
Simply put? Check out your owners’ manual to find the recommended fuel for your vehicle.
Does it say, “Manufacturer recommends regular gasoline”? Then paying for premium will be a waste of money. Stick with regular lower-octane fuel.
Does it say, “Manufacturer says premium gasoline is required”? Then you’ll want to fuel up with premium the majority of the time. You may be able to step down to mid-range from time to time, and regular will work in a pinch, but you’ll need to be alert for knocking – if your engine is knocking often, that can produce lasting damage!
Does it say, “Manufacturer says premium gasoline is recommended”? Then you can likely use regular or mid-range octane fuels with little to know trade-off of power and fuel-economy. Unless you hear knocking, or if the power output drops too low for your liking, you can roll with lower octane ratings for as long as you want..
Does it say, “Manufacturer says Flex Fuel is recommended,” or mention E85 or FFV in the manual or on the rear badge of your vehicle? Then you can use E85 fuel to get better fuel mileage and know that you are putting out lower greenhouse gas emissions. However, you’re still free to run on standard fuel!
What About TOP TIER?
The TOP TIER program was a joint effort of fuel retailers to provide high quality fuel. The retailers are required to not use organometallic additives such as MMT or Ferrocene in their fuels. Furthermore, the gasoline grades must be treated with an approved TOP TIER Detergent Gasoline additive at correct concentrations to remain in the program.
What does this mean? In the end, not all that much. It’s a voluntary program and does not mean that a location without the label is any worse. You can find a list of all TOP TIER brands here.
Just like humans, what you put into your car is important in getting the most out of it. Feed your vehicle the type of gas that is right for it, and you’ll get years of great performance out of your car, truck, or SUV!