Do octane boosters really work? | Fuel Tips

We want it all and we don’t want to pay for it. Sound familiar? Of course it does. We’ve all been there. 

So when it comes to race fuel, instead of paying for the good stuff, why not buy an additive and mix up your own? You can do that, notes Zachary J. Santner, manager of product engineering and business optimization at Sunoco, but there are some caveats.

First, he says, realize that not all octane boosters and race gas concentrates are equal. Octane boosters–picture the brightly colored bottles full of hopes and promises lining the shelves at the local auto parts store–often contain octane-raising aromatics like toluene. 

Note that we’re talking about very small quantities of active ingredients, and the effects aren’t always as good as promised: An octane point, the usual claim, only equates to one-tenth of an octane number. (So, for example, boosting 91 pump fuel by an octane point yields an octane rating of 91.1; now picture how many bottles you’ll need to significantly move the needle.)

The story changes a bit when discussing methylcyclopentadienyl manganese tricarbonyl, aka MMT. This additive is often found in products billed as race gas concentrates, and Santner notes that it’s rather effective at raising octane–but with some considerations: MMT degrades in sunlight, and it can produce an orange soot. “MMT is still a metal,” he notes. “You can’t burn it, but you can oxidize it.” Additives containing MMT generally also cost more than those built upon aromatics.

But all these fuel additives rely on one common ingredient: the pump fuel, which, as Santner notes, can vary depending on the season and location, never mind the retailer. A 93-octane fuel sold in Miami during the summer, for example, will feature a different blend than a 93 delivered to a Michigan station during the winter. Sunoco race fuels, he continues, are always mixed to consistent recipes year-round.

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