Motul Super Octane Booster is a 300ml petrol additive that raises the effective octane of the fuel in the tank. Octane measures a fuel’s resistance to detonation, and higher-compression, forced-induction and ignition-advanced engines need that resistance or the mixture ignites uncontrollably ahead of the flame front, which is heard as knock and does real damage to pistons and ring lands quickly. It is a useful safety margin when fuel quality is uncertain, when running an engine tuned for a higher grade than the pump nearest you offers, or at a track day. Follow the dose rate for your tank size rather than over-adding. It does not replace correct tuning, and this is the petrol version only.