Honda WT20X Manuel De L'utilisateur page 18

Gasoline spoils very quickly depending on factors such as light
exposure, temperature and time.
In worst cases, gasoline can be contaminated within 30 days.
Using contaminated gasoline can seriously damage the engine
(clogged carburetor, stuck valve).
Such damage due to spoiled fuel is disallowed from coverage by the
warranty.
To avoid this please strictly follow these recommendations:
Only use specified gasoline (see page
Use fresh and clean gasoline.
To slow deterioration, keep gasoline in a certified fuel container.
If long storage (more than 30 days) is foreseen, drain fuel tank and
carburetor (see page
Gasolines containing alcohol
If you decide to use a gasoline containing alcohol (gasohol), be sure its
octane rating is at least as high as that recommended by Honda.
There are two types of ''gasohol'': one containing ethanol, and the
other containing methanol.
Do not use gasohol that contains more than 10% ethanol.
Do not use gasoline containing more than 5% methanol (methyl or
wood alcohol) and that does not also contain co-solvents and
corrosion inhibitors for methanol.
Fuel system damage or engine performance problems resulting
from the use of gasoline that contains more alcohol than
recommended is not covered under the warranty.
Before buying gasoline from an unfamiliar station, first determine if
the gasoline contains alcohol, if it does, find out the type and
percentage of alcohol used.
If you notice any undesirable operating symptoms while using a
particular gasoline. Switch to a gasoline that you know contains less
than the recommended amount of alcohol.
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