lowoctane

Lowoctane is a term used to refer to fuels with a relatively low octane rating, designed to resist knocking less effectively than higher-octane fuels. In everyday usage, it contrasts with high-octane fuels that are formulated to withstand higher compression without premature ignition. The term can apply to gasoline blends that fall near the lower end of a regional octane scale, and to fuels designed for older or lower-compression engines.

Octane rating measures a fuel's resistance to auto-ignition under compression. In the United States, fuel octane is reported as the Anti-Knock Index (AKI), the average of Research Octane Number (RON) and Motor Octane Number (MON). A common US regular is 87 AKI, while mid-grade and premium fuels are higher. In Europe and many other regions, octane is given as RON, with typical values around 95–98 for premium and 91–93 for regular. Therefore, what counts as "lowoctane" depends on the regional standard.

Engine compatibility: Modern engines with high compression ratios and turbocharging are calibrated for higher-octane fuels to avoid knocking. Using lowoctane fuel in such engines can reduce performance, increase fuel consumption, or trigger engine knock protection controls. Conversely, engines designed for low-octane fuel may operate normally on such blends. Refinery and additive packages may also influence performance beyond the octane number alone.