2009 Toyota Corolla Owners Manual - Page 344

6 -1 . Spe c ific a t ions Fue l infor m at ion You must only use unleaded gasoline in your vehicle. Unleaded gasoline with an Octane Rating of 87 (Research Octane Number 91) or higher is required for optimum engine performance. At minimum, the gasoline you use should meet the specifications of ASTM D4814 in the U.S.A. and CGSB3.5-M93 in Canada. n Fuel tank opening for unleaded gasoline To help prevent incorrect fueling, your Toyota has a fuel tank opening that only accommodates the special nozzle on unleaded fuel pumps. n If your engine knocks l Consult your Toyota dealer. l You may occasionally notice light knocking for a short time while accelerating or driving uphill. This is normal and there is no need for concern. n Gasoline quality In very few cases, driveability problems may be caused by the brand of gasoline you are using. If driveability problems persist, try changing the brand of gasoline. If this does not correct the problem, consult your Toyota dealer. n Gasoline quality standards l Automotive manufacturers in the U.S., the Europe and Japan have developed a specification for fuel quality called World-Wide Fuel Charter (WWFC) that is expected to be applied worldwide. l The WWFC consists of four categories that are based on required emission levels. In the U.S., category 4 has been adopted. l The WWFC improves air quality by lowering emissions in vehicle fleets, and improves customer satisfaction through better performance. 428