2000 Lexus GS 300 Owners Manual - Page 415

ENGINE Use of unleaded fuel with an octane number or rating lower than stated above will cause persistent heavy knocking. If severe, this will lead to engine damage. If your engine knocks ...If you detect heavy knocking even when using the recommended fuel, or if you hear steady knocking while holding a steady speed on level roads, consult your Lexus dealer. However, now and then, you may notice light knocking for a short time while accelerating or driving up hills. This is no cause for concern. Gasoline containing detergent additives Lexus recommends the use of gasoline that contains detergent additives to avoid build-up of engine deposits. However, all gasoline sold in the U.S. contains detergent additives to keep clean and/or clean intake systems. Quality gasoline Automotive manufacturers in the U.S., Europe and Japan have developed a specification for quality fuel named World-Wide Fuel Charter (WWFC) that is expected to be applied world wide. The WWFC consists of three categories that depend on required emission levels. In the U.S., category 3 has been adopted. The WWFC improves air quality by providing for better emissions in vehicle fleets, and customer satisfaction through better vehicle performance. 395