1998+ Mercury Mariner 25HP Bigfoot Service Manual, Page 36Get this manual
MAINTENANCE
Fuel System
IMPORTANT: Gasoline containing alcohol (ethanol or methanol) can cause formation of acid during storage and can damage the fuel systemIf the gasoline being use contains alcohol, it is advisable to drain as much of the remaining gasoline as possible from the fuel tank, remote fuel line, and engine fuel system
Protecting External Outboard Components