ENGINE DIVISION SERVICE MANUAL
ENGINE FUEL REQUIREMENTS
Your gasoline engine is designed to operate
efficiently in normal operations on "Regular" grade fuels
of at least 91 RON (Research Octane Number) or 86.5
anti-knock index designation. (The latter figure is now
generally posted on fuel dispensing pumps.) "Low Lead"
fuel containing at least .13 gpl (0.5 gpg) lead, or the
equivalent additive, per gallon may be used.
Continuous use of gasoline which is completely free
phosphorus, is not recommended . Prolonged use of
such fuel can cause excessive exhaust valve seat wear
resulting in loss of emission control, poor performance
and possible engine failure.
Because of this, it is recommended that you alternate
to regular grade fuel every fourth tank. The alternating
fuel method is not necessary with use of low lead
content fuel as it can be successfully used without any
harm to your engine.
Use of a fuel which is too low in antiknock quality will
result in "spark knock." Since anti-knock quality of all
"regular" grade gasolines is not the same and factors
such as altitude, terrain and air temperature affect
operating efficiency, knocking may result even though
you are using the grade of fuel recommended for your
Continued engine operation under "Spark Knock"
conditions can cause severe engine damage. At these
times a higher antiknock quality gasoline is required to
prevent engine damage. If knocking persists with higher
grade fuel, it is recommended an IH or suitably qualified
service outlet be contacted as engine repairs may be
Fig. 96 Engine Fuel Requirements.
CGES-215 Page 56
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