Rick's Free Auto Repair Advice

Which gasoline is best?

gasoline nozzle

Best gasoline?

What’s the best gasoline for your vehicle?

Do you think premium gasoline is better for your car or is it just one of those gasoline myths? How about the advice that premium gasoline doesn’t contain ethanol so it’s better for your small engine? Is that true? Or the myth that premium gasoline contains more detergents so it’s better than regular?

Sorting through the gasoline myths

Buckle up because we going for a drive through gasoline myth land.

Is Top Tier Gas better for your engine?

This is a tough one because there’s actually no authoritative Society of Automotive Engineers study or independently published scientific evidence that Top Tier gasoline is any better than non-Top Tier gasoline.

Top Tier gasoline was developed because some car makers believe that the current EPA minimum detergent guidelines don’t go far enough to maintain fuel system cleanliness and they state that on the TopTiergas.com website:

“Since the minimum additive performance standards were first established by EPA in 1995, most gasoline marketers have actually reduced the concentration level of detergent additive in their gasoline by up to 50%.  As a result, the ability of a vehicle to maintain stringent Tier 2 emission standards have been hampered, leading to engine deposits which can have a big impact on in-use emissions and driver satisfaction.”

However, in the Top Tier testing requirements, they also state:

“Deposit Control Additive Requirements.   The deposit control additive used to meet the performance Standards described in 4.3 shall meet the substantially similar definition under Section 211(f) of the Clean Air Act. Also, the additive shall be certified to have met the minimum deposit control requirements established by the U.S. Environmental Protection Agency (EPA) in 40 CFR Part 80. Lastly, the additive shall be registered with the EPA in accordance with 40 CFR Part 79.” —TopTierGas.com

So basically Top Tier gas requires the same detergent additives that the EPA requires of all gasoline sellers. In addition, fuel system cleaners have come a long way since the EPA established the standard and some of the newest additives are far more efficient than the older ones, so they don’t require as high a dose.

So it’s really not accurate to compare the number of ounces of additive in a gallon of gas without comparing the effectiveness of those additives. Bottom line; the EPA enforces their minimum detergent standards. If a brand of gasoline is consistently under-performing, you’d hear about it.

Also, to become a Top Tier seller, the refinery must use only the detergent approved by the Top Tier organization:

“The performance testing costs will vary depending on the independent ISO 17025 certified lab that is hired to run the tests. The total cost of all testing can be in the range of $25,000 – $30,000. The detergent additive company pays for the testing; they select the treat rate that they think will pass the TOP TIER performance specification limits. Once they have a Pass, they inform their fuel marketing customers of the detergency treat rate required to be in the TOP TIER program. It is then up to the fuel marketers to decide if they want to treat their gasoline at the prescribed detergency treat rate.” —TopTierGas.com

And, the gasoline supplier must pay a fee to the TopTierGas organization. Again, read this from their website:

What does it cost to sign up for the TT program?
There is an annual fee based on the number of service stations owned by the fuel marketer. —TopTierGas.com

So TopTier gas is a money maker for the car companies that recommend its use and you pay the costs.

If non TopTier gasoline was really as bad as you’re led to believe, then we should be seeing massive problems with fuel injector clogging and fuel system deposits in engines that don’t recommend Top Tier gasoline. And, if Top Tier gasoline was that much better why aren’t the other car makers recommending it as well? I mean, it doesn’t cost the car maker any money to recommend a supposedly “better” gasoline for their engines. But we’re not seeing that.

More importantly, where are the scientific studies from the Society of Automotive Engineers (SAE)? Wouldn’t you think they’d have published peer-reviewed scientific articles comparing TopTier gas to non-TopTier gas? I can’t locate any SAE studies. Instead, you simply have to take the Top Tier organizations’ word for it that their gas is better. Absent that proof and the fact that other car brands work fine with the EPA minimum detergent levels, you have to wonder why the car makers are having a problem with non Top Tier gasoline when their competitors aren’t.

Is premium gasoline ethanol-free?

If you buy premium gas from a station that specializes in selling ethanol-free gas, then it’s ethanol free. If you buy it at a regular gas station, it may or may not contain ethanol. 95% of all gas sold in the U.S. contains ethanol. Period. If it doesn’t say ethanol-free, chances are it has ethanol. Premium gasoline, by definition, does NOT automatically mean it’s ethanol-free.

Does premium gas have detergent?

No. Some refineries and gasoline brands add extra fuel system cleaning additives. But premium gasoline, by definition, does NOT automatically contain more or better detergent. That’s a myth.

Is premium gasoline better for your small engine?

No. Premium gas may or may not contain ethanol. It doesn’t have a longer shelf life, doesn’t add more power, and isn’t required by most small engine manufacturers. Most small engines are made for regular gas and start and run better with regular.

More power with premium gasoline?

Myth! A fuel’s octane rating represents the fuel’s ability to resist DETONATION. When used in a high compression engine, premium gasoline ignites on time and provides gasoline octane rating on gas pumpa controlled burn better than a lower octane fuel used in the same engine.

But a fuel’s octane rating has NOTHING to do with its energy content. If you use a higher than recommended octane gas in an engine designed to run on regular gas will NOT get you more performance. You will not get better gas mileage, more power, or better overall performance unless your engine is carboned up with deposits. Then premium gas can reduce or eliminate detonation.

You may however, see a slight MPG differences between two different gasoline brands with the same octane rating. That’s because each refiner’s recipe differs slightly to attain their gasoline’s octane rating, and some of those chemicals may result in a slightly higher btu content. But the actual difference in energy content from one refiner’s 87-octane gasoline to another 87-octane gasoline is small and may account for an MPG increase of 1-MPG at max.

So, if your late model vehicle is rated for 87 octane gas and the engine is equipped with a knock sensor, you might get more power and performance from premium gas. Here’s why.

Late model cars have a knock sensor to detect detonation (the air/fuel mixture igniting from carbon deposits in the combustion chamber). If the engine control computer detects detonation, it responds by retarding the spark, and THAT retarded spark timing is what reduces power and performance. So when you move to a higher octane fuel and the knocking stops, the computer re-sets back to normal spark timing and you experience more power and performance. It’s the elimination of knock and the restoration of normal spark timing that allows your engine to run at maximum performance. But keep in mind that you’ll only see that increase IF your engine has carbon deposits that cause knock. If your engine is clean, you’ll get no increase in performance from using a higher octane fuel.

Is one brand of gas better than another?

Gasoline is made from over 150 different ingredients and every refiner blends their gas according to their own recipe. The recipe varies based on the time of year and cost of the individual components on the open market. If one component rises in price, the refiner will adjust the recipe to compensate by using a less costly component. So you may notice a performance difference between brands in your car. But fill a different vehicle with that same gas and it may not perform any better. So you can’t make any kind of general statement that Brand X is better for all cars.

When it comes to additives, there was a big difference between “cheap” gas and name brand gas in the old days. Now that the EPA requires a minimum level of detergent additives, there’s little to no recognizable difference between brands.

Are Fuel injector cleaners any good?

Lots of companies sell pour-in fuel injector cleaners and fuel system cleaners. Bottle of Chevron Techron Complete Fuel System cleanerThe only two cleaners proven effective are polyisbutylamine (PIBA) and polyetheramine (PEA). Chevron Techron, Gummout, GM top cylinder cleaner and a few others have those cleaners. See this post for more information on fuel system cleaners.

©, 2016 Rick Muscoplat






Posted on by Rick Muscoplat

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