Toyota 2009 Avalon Owner's Manual page 454

6-1. Specifications
NOTICE
n Notice on gasoline quality
Do not use leaded gasoline.
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Leaded gasoline can cause damage to your vehicle's three-way catalytic
converters causing the emission control system to malfunction.
Do not use gasohol other than that stated here.
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Other gasohol may cause fuel system damage or vehicle performance
problems.
Using unleaded gasoline with an octane number or rating lower than that
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stated here will cause persistent heavy knocking.
At worst, this will lead to engine damage.
Fuel-related poor driveability
n
If after using a different type of fuel, poor driveability is encountered (poor
hot starting, vaporization, engine knocking, etc.), discontinue the use of that
type of fuel.
When refueling with gasohole
n
Take care not to spill gasohol. It can damage your vehicle's paint.
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