5.11 Will oxygenated gasoline damage my vehicle?
Description
This article is from the Gasoline FAQ, by Bruce Hamilton with numerous contributions by others.
5.11 Will oxygenated gasoline damage my vehicle?
The following comments assume that your vehicle was designed to operate on
unleaded, if not, then damage such as exhaust valve seat recession may occur.
Damage should not occur if the gasoline is correctly formulated, and you
select the appropriate octane, but oxygenated gasoline will hurt your pocket.
In the first year of mandated oxygenates, it appears some refiners did not
carefully formulate their oxygenated gasoline, and driveability and emissions
problems occurred. Most reputable brands are now carefully formulated.
Some older activated carbon canisters may not function efficiently with
oxygenated gasolines, but this is a function of the type of carbon used.
How your vehicle responds to oxygenated gasoline depends on the engine
management system and state of tune. A modern system will automatically
compensate for all of the currently-permitted oxygenate levels, thus your
fuel consumption will increase. Older, poorly-maintained, engines may
require a tune up to maintain acceptable driveability.
Be prepared to try several different brands of oxygenated or reformulated
gasolines to identify the most suitable brand for your vehicle, and be
prepared to change again with the seasons. This is because the refiners can
choose the oxygenate they use to meet the regulations, and may choose to set
some fuel properties, such as volatility, differently to their competitors.
Most stories of corrosion etc, are derived from anhydrous methanol corrosion
of light metals (aluminum, magnesium), however the addition of either 0.5%
water to pure methanol, or corrosion inhibitors to methanol-gasoline blends
will prevent this. If you observe corrosion, talk to your gasoline supplier.
Oxygenated fuels may either swell or shrink some elastomers on older cars,
depending on the aromatic and olefin content of the fuels. Cars later than
1990 should not experience compatibility problems, and cars later than 1994
should not experience driveability problems, but they will experience
increased fuel consumption, depending on the state of tune and engine
management system.
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