2007 Lexus GS 350 Owners Manual - Page 580

6-1. Specifications Fuel information Your vehicle must use only unleaded gasoline. Premium unleaded gasoline with an Octane Rating 91 (Research Octane Number 96) or higher 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 Lexus has a fuel tank opening that only accommodates the special nozzle on unleaded fuel pumps. n If premium gasoline is not available If 91 Octane cannot be obtained, you may use unleaded gasoline with an Octane Rating as low as 87 (Research Octane Number 91). However, use of unleaded fuel with an Octane Rating lower than 91 may result in engine knocking (GS350 only: or drastically reduce output to protect itself while driving with heavy load). Persistent knocking can lead to engine damage and should be corrected by refueling with higher octane unleaded gasoline. n If your engine knocks l Consult your Lexus 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 Lexus dealer. 508