Jeep 2015 Grand Cherokee - Owner Manual - Manual (Page 525)

5.7L Engine — If Equipped
This engine is designed to meet all emis-
sions regulations and provide satisfactory
fuel economy and performance when us-
ing high-quality unleaded gasoline having
an octane range of 87 to 89. The manufac-
turer recommends the use of 89 octane for optimum
performance. The use of premium gasoline is not recom-
mended, as it will not provide any benefit over regular
gasoline in these engines.
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 experi-
ence these symptoms, try another brand of gasoline
before considering service for the vehicle.
Over 40 auto manufacturers worldwide have issued and
endorsed consistent gasoline specifications (the World-
wide Fuel Charter, WWFC) which define fuel properties
necessary to deliver enhanced emissions, performance,
and durability for your vehicle. The manufacturer recom-
mends the use of gasolines that meet the WWFC speci-
fications if they are available.
Reformulated Gasoline
Many areas of the country require the use of cleaner
burning gasoline referred to as “Reformulated Gasoline.”
Reformulated gasoline contain oxygenates and are spe-
cifically blended to reduce vehicle emissions and im-
prove air quality.
The manufacturer supports the use of reformulated gaso-
line. Properly blended reformulated gasoline will pro-
vide excellent performance and durability of engine and
fuel system components.
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