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gasolines, and in some circumstances may result in
poorer performance.
4.0L Gasoline Engine
The 4.0L engine is designed to meet all
emissions regulations and provide satisfac-
tory fuel economy and performance when
using high-quality unleaded gasoline hav-
ing an octane range of 87 to 89. The manu-
facturer recommends the use of 89 octane
for optimum performance. The use of premium gasoline
is not recommended. Under normal conditions, the use of
premium gasoline will not provide a benefit over high-
quality regular and mid-grade gasolines, and in some
circumstances may result in poorer performance.
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 automobile manufacturers around the world
have issued and endorsed consistent gasoline specifica-
tions (the World Wide Fuel Charter, WWFC) to define
fuel properties necessary to deliver enhanced emissions,
engine performance, and durability for your vehicle. The
manufacturer recommends the use of gasolines that meet
the WWFC specifications if they are available.
Reformulated Gasoline
Many areas of the country require the use of cleaner
burning gasoline referred to as “Reformulated Gasoline”.
Reformulated gasolines contain oxygenates, and are spe-
cifically blended to reduce vehicle emissions and im-
prove air quality.
378 STARTING AND OPERATING