1998 Toyota Tacoma Owners Manual - Page 139

'98 Tacoma (U) OCTANE RATING Select Octane Rating 87 (Research Octane Number 91) or higher. Use of unleaded gasoline with an octane rating or research octane number lower than stated above will cause persistent heavy knocking. If it is 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 Toyota dealer. However, now and then, you may notice light knocking for a short time while accelerating or driving up hills. This is no need of concern. GASOLINES ADDITIVES CONTAINING DETERGENT IMPROVED GASOLINES The American Automobile Manufacturers Association (AAMA) has developed a specification of improved gasolines. The AAMA specification offers optimal fuel information for better vehicle performance and better protection of your engine. Toyota recommends the use of gasolines that meet the AAMA specification, if available, for improved driveability and emission control system. GASOLINES CONTAINING MTBE Gasolines that contain MTBE (Methyl Tertiary-Butyl Ether) are available in the market. If you use a gasoline mixed with MTBE, make certain that it does not contain more than 15 % of MTBE. If the use of gasolines containing MTBE causes poor driveability and/or poor fuel economy, you should discontinue the use of fuels containing MTBE. GASOLINES CONTAINING MMT Some gasolines contain an octane- enhancing additive called MMT (methylcyclopentadienyl manganese tricarbonyl). Toyota does not recommend the use of gasolines that contain MMT. If fuels containing MMT are used, your emission control system may be adversely affected. The Malfunction Indicator Lamp on the instrument cluster may come on. If this happens, contact your Toyota dealer for service. GASOLINES CONTAINING ALCOHOL If you use gasohol in your Toyota, be sure that it is unleaded, has an octane rating no lower than 87 and does not contain more than 10 % ethanol. Gasohol is a mixture of gasoline and ethanol. Toyota does not recommend the use of gasolines containing methanol. If you use gasoline containing methanol, use only gasoline meeting the requirements above and also containing less than 5 % methanol with cosolvents and corrosion inhibitors for methanol. Toyota recommends use of gasolines that contain detergent additives to avoid build-up of engine deposits. For further details, ask your Toyota dealer or a local gasoline retailer. 139