For starters, use a gasoline with the AKI recommended by your owner's manual. Using gasoline with an antiknock rating higher than that required to prevent knock will not improve a vehicle's performance, including its power, unless the vehicle is equipped with a knock sensor and the car's computer is controlling the engine to reduce or eliminate knock on the lower octane grade fuels. Many late model and high-performance engines fall into this category.
There are two reasons why your vehicle might knock on a gasoline with the AKI recommended by the owner's manual:
- The engine is at the upper end of the octane number requirement range.
- Combustion chamber deposits in your engine are higher than usual.