2005 Lexus GX 470 Owners Manual - Page 576

ENGINE Octane rating Select Octane Rating 87 (Research Octane Number 91) or higher. For improved vehicle performance, the use of premium unleaded gasoline with an Octane Rating of 91 (Research Octane Number 96) or higher is recommended. 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, occasionally, you may notice light knocking for a short time while accelerating or driving up hills. This is normal and there is no need for concern. 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 four 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. Cleaner burning gasoline Cleaner burning gasoline, including reformulated gasoline that contains oxygenates such as ethanol or MTBE is available in many areas. Lexus recommends the use of cleaner burning gasoline and appropriately blended reformulated gasoline. These types of gasoline provide excellent vehicle performance, reduce vehicle emissions, and improve air quality. 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. 551