STP Octane Booster (5.25 fluid ounces) This two-in-one formula boosts octane and cleans the fuel intake system to restore lost performance. Helps restore lost power and acceleration and reduces knocking and pinging. Contains MMT + Synthetic Technology. Compatible with any gas engine including cap-less gas systems. Simply empty one bottle before or after fueling. For over 60 years and for more miles than anyone can count STP has been one of the most trusted names in automotive care.