Expert Advice

Gasoline is rated by its ability to resist engine knock, a result of premature ignition of the compressed fuel and air mixture in one or more cylinders. This rating is referred to as the octane rating.

In the US, we generally find two or three grades of gasoline: Regular, MidGrade and Premium, ranging from 87 to 93. There are also variations between the states.

There are some differences between how octane is reported in the US and in much of the rest of the world. The reason is that there are actually two different protocols for determining octane. If you fill up in the US, there would be a tag on the gas pump that says MON + RON / 2.

That means that the RON (Research Octane Number) and the MON (Motor Octane Number) are combined and divided by two. That’s the way octane is figured in America. In Europe and much of the rest of the world, octane is based only on RON by itself. The two protocols will result in two different numbers for the same gas and these numbers are usually about ten numbers different.

The net result is that 91 octane in the US is the same as 97 or 99 in Europe. To figure that, you might get the same gasoline that tests 97 RON and 88 MON, and in the US that would be 91 (MON + RON / 2) and in Europe it would be 97 RON. It’s the exact same gas.

You should follow the manufacturer’s recommendation. While Regular is recommended for most cars, some cars with high compression engines require a higher octane to prevent knock and ping.

But, listen to your car! At Dyno-tab®, we say, Silence is Golden! When you hear knock and ping in your engine, you recognize that it is not the normal engine sound. Some degree of knock and ping may not be harmful to your engine, but continued or heavy knocking can definitely result in engine damage.

The recommended gasoline for most cars in the US is “Regular”, but when we fill up, there is a temptation to purchase premium, even if regular is all our car manufacturer recommends. There is a perception that premium fuel is better for our cars than lower grades, so we are often willing to pay a little extra.

If you are buying Regular or Mid Grade and hear knocking, add one Dyno-tab® Fuel Treatment to the tank (at the recommended treat rate) and listen for the difference. If knocking persists, you may need to visit your repair shop.

Data shows that, depending on the aromatic characteristics of the fuel, one Dyno-tab® multipurpose tablet that treats 16 gallons, will typically add:

  • 1 to 2 (10 to 20 points) numbers to 87-octane gasoline
  • 1 (10 points) number to 89-octane gasoline
  • .5 (5 points) number to 92-octane gasoline

Like most other octane boosters, the Dyno-tab® chemistry is a parabolic compound. This means that at a certain point, the addition of more Dyno-tab® does not result in increased octane. The octane rating of readily available fuel varies around the world. In many parts of the United States and in some overseas markets, 85-octane and even lower grades of gasoline are offered for sale.

The result of using Dyno-tab® in these lower grades of gasoline is very dramatic. Dyno-tab® can add up to 3 to 4 octane numbers – an astounding 40 octane points. In certain Eastern European and former Soviet Union markets, 78-octane gasoline is routinely sold and Dyno-tab® can add up to 7 numbers (70 octane points) to this fuel.