Flex/Variable Fuel Systems

Flexible-fuel systems (sometimes called Variable-Fuel) are generally installed by the manufacturer of the vehicle and are not available as a conversion kit. Flexible fuel vehicles are vehicles that can run on a mixture of methanol and gasoline. They have sensors that can determine the ratio of methanol to gasoline. As the level of methanol increases, the sensors send this information to the computer. The computer will then richen the fuel mixture and advance the timing, with the reverse true as the level qf gasoline increases. Ethanol mixtures can also be detected by fuel sensors, so these vehicles can also operate on a mixture of ethanol and gasoline.

It has been found that if a gasoline level of at least 15% is maintained, these vehicles are much easier to start in cold weather. The fuel in variable-fuel vehicles is sometimes called M85. TXhe "M" stands for methanol and the 85 stands for 85%-85% because the methanol levels in the fuel mixture shouldn't rise above 85% to allow an easier start in cold weather.

These vehicles must also use special oil only available from the manufacturer to prevent the methanol from washing down the piston rings and scoring the cylinder walls.