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Octane Booster vs. Premium

MCN February 2020

Is there any difference in using an octane booster, as opposed to paying higher pump prices for premium?


Octane boosters are often marketed for power gains, when their true objective is to reduce abnormal combustion events, such as preignition and detonation. However, there can be power gains with the right engine enhancements, higher octane and certain fuel additives. Most inexpensive octane boosters are alcohol based and do a good job at ‘drying’ fuel (reducing water content), cleaning the fuel system and decreasing the chance of detonation and preignition.

But these abnormal events are indicative of ignition that is advanced too far, lean fueling, air leaks, hot spots and soot or carbon buildup. Using additives is not exactly convenient, nor are most fuel systems designed to handle the solvent effects of some chemicals in the long term.

Heavy use of alcohol additives may attack the rubbers in the fuel system, particularly the boots before and after the carburetor, as well as seals and O-rings.

Unfortunately, once damaged, these parts may no longer be readily available, and used parts may be just as aged. Petroleum based boosters and chemical boosters such as toluene, trimethylbenzene and tetraethyllead do a great job at reducing abnormal combustion and can allow higher compression ratios and ignition advance with improved power gains, but they are not something you want to run as an additive.

Race engines use blended, somewhat-stabilized race gas to make sure the dose of antiknock elements, oxygen content and whatever other magic they use for power and anti-knock is consistent. Adding fuel additives to a tank is not very accurate, nor does it always blend well with pump fuel. Some can even cause the alcohol and gas to separate.

I use additives occasionally for cleaning the system and alternate from alcohol to petroleum based, but only a couple of times a year. I recommend petroleum-based stabilizers any time the vehicle will sit for a month or longer.

If I want an octane booster, I’ll choose a quality high-octane pump fuel or with a modified engine, race fuel.  Adding boosters may provide a smoother running and cooler operating engine, if it is experiencing abnormal combustion, but it will also increase fuel costs significantly.

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