An anti-knock agent is a gasoline additive that increases the temperature and pressure at which auto-ignition occurs. It helps to reduce engine knocking and raising the octane rating of the fuel.

While knocking is no longer as widespread a problem thanks to the current state of anti-knock sensor technology, it can be an issue for vehicles with gasoline direct-injection engines.

When you are buying gasoline with a particular octane number, joke's on you. There is little or no octane in there, because octane will blow you engine up. A little primer on anti-knock additives.

Charles K. Westbrook, William J. Pitz, William R. Leppard, The Autoignition Chemistry of Paraffinic Fuels and Pro-Knock and Anti-Knock Additives: A Detailed Chemical Kinetic Study, SAE Transactions, ...

"Addressing long-standing mysteries behind anti-wear motor oil additive." ScienceDaily. ScienceDaily, 13 March 2015. <www.sciencedaily.com / releases / 2015 / 03 / 150313130937.htm>.

Will octane additives fix the knocking sound if I put regular gas in a car requiring premium? LOU TROTTIER Special to The Globe and Mail Published December 14, 2016 ...

Your engine may need premium fuel and be unable to compensate for regular gas (today's anti-knock sensor technology lets many engines run on any gasoline grade, but the sensor could be bad).