Porsche 911 Carrera - Manual (Page 248)

Fuel Recommendations
Your Porsche is equipped with catalytic converters
and must use UNLEADED FUEL ONLY.
Your engine is designed to provide optimum
performance and fuel economy using unleaded
premium fuel with an octane rating of 98 RON
(93 CLC or AKI). Porsche therefore recommends
the use of these fuels in your vehicle.
Porsche also recognizes that these fuels may
not always be available. Be assured that your
vehicle will operate properly on unleaded premium
fuels with octane numbers of at least 95 RON
(90 CLC or AKI), since the engine’s “Electronic
Octane™ knock control” will adapt the ignition
timing, if necessary.
The use of UNLEADED FUEL ONLY is critically
important to the life of the catalytic convert-
ers. Deposits from leaded fuels will ruin the
converters and make it ineffective as an emis-
sion control device.
Cars with catalytic converters have a smaller fuel
tank opening, and gas station pumps have smaller
nozzles. This will prevent accidental pumping of
leaded fuel into cars with catalytic converters.
Unleaded fuels may not be available outside the
continental U.S. and Canada. Therefore, we
recommend you do not take your car to areas
or countries where unleaded fuel may not be
available.
Octane ratings
Octane rating indicates a fuel’s ability to resist
detonation. Therefore, buying the correct octane
gas is important to prevent engine “damage”.
The RON octane rating is based on the research
method. The CLC (U.S. Cost of Living Council
octane rating) or AKI ( antiknock index) octane
rating usually displayed on U.S. fuel pumps is
calculated as research octane number plus motor
octane number, divided by 2, that is written as:
RON + MON R + M
2
or
2
The CLC or AKI octane rating is usually lower than
the RON rating:
For example: 95 RON equals 90 CLC or AKI
Fuels containing alcohol and ether
Some areas of the U.S. require oxygenated fuels
during certain portions of the year. Oxygenated
fuels are fuels which contain alcohols (such as
methanol or ethanol) or ether (such as MTBE).
Under normal conditions, the amount of these
compounds in the fuel will not affect driveability.
You may use oxygenated fuels in your Porsche,
provided the octane requirements for your vehicle
are met. We recommend, however, to change
to a different fuel or station if any of the following
problems occur with your vehicle:
– Deterioration of driveability and performance.
– Substantially reduced fuel economy.
– Vapor lock and non-start problems, especially
at high altitude or at high temperature.
– Engine malfunction or stalling.
Fuels containing MMT
Some North American fuels contain an octane
enhancing additive called methylcyclopentadienyl
manganese tricarbonyl (MMT).
If such fuels are used, your emission control
system performance may be negatively affected.
The check engine warning light on your instrument
panel may turn on. If this occurs, Porsche recom-
mends you stop using fuels containing MMT.
246
Maintenance, Car Care