What fuel does the 2019 Honda Civic Si use?

For optimal performance, it is advised to fill your 2019 Honda Civic Si with premium unleaded gasoline that has an octane of 91 or higher. Using a lower octane can lead to a loud metallic knocking sound and potential engine damage over time. It is recommended to choose gasoline labeled as TOP TIER Detergent Gasoline as these fuels do not contain metallic additives and include the necessary detergents to prevent deposits in the fuel system, engine, and emission control system. When refueling the car, ensure the engine is turned off and use the master door lock switch to unlock the driver's door, which will also unlock the fuel door. To open the fuel door, push in on the right side of it to unlatch. The fuel filler opening is specifically designed for gas station nozzles, so inserting anything smaller could harm the opening.