Fuel Requirements (Gasoline Engines) - Jeep 2007 Liberty Owner's Manual

FUEL REQUIREMENTS (GASOLINE ENGINES)

Your engine is designed to meet all emis-
sions regulations and provide excellent
fuel economy and performance when us-
ing high quality unleaded gasoline having
an octane rating of 87. The use of premium
gasoline is not recommended. The use of
premium gasoline will provide no benefit over high
quality regular gasoline, and in some circumstances may
result in poorer performance.
Mid-grade gasoline (89 octane) will enhance engine per-
formance during the following conditions:
• Hot weather
• Towing
• Hard accelerations
• Hilly terrain
• Low humidity
STARTING AND OPERATING 273
Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and immediate service is
required.
Poor quality gasoline can cause problems such as hard
starting, stalling and hesitations. If you experience these
symptoms, try another brand of "regular" gasoline be-
fore considering service for the vehicle.
Over 40 auto manufacturer's world wide have issued and
endorsed consistent gasoline specifications (the World-
wide Fuel Charter, WWFC) to define fuel properties
necessary to deliver enhanced emissions, performance,
and durability for your vehicle. The manufacturer recom-
mends the use of gasoline that meets the WWFC speci-
fications if they are available.
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