Honda EG3500X Owner's Manual page 24

MTBE (methyl tertiary butyl ether)
You may use gasoline containing up to 15% 4TBE by volume.
Before using an oxygenated fuel, try to confirm the fuel's contents. Some
states (provinces in Canada) require this information to be posted on the
pump. If you notice any undesirable operating symptoms, switch to a
conventional unleaded gasoline. Fuel system damage or performance
problems resulting from the use of an oxygenated fuel are not the
responsibility of Honda and are not covered under warranty.
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Oxygenated fuels can damage paint and plastic. Be
careful not to spill fuel when filling your fuel tank. Damage caused by
spilled fuel is not covered under warranty.
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