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 TM 9-8000
after 1980. The SF oil is designed to meet the demands
take up bearing clearances or prevent bearing scuffing.
of the small, high-revving engines that are popular due to
In cold weather, heavy oil would not give adequate
the trend toward downsizing of vehicles. An SF oil can
lubrication because its flow would be sluggish; some
be used In all automotive vehicles. API service ratings
parts might not receive oil at all.
have related military specifications designations.
b. Viscosity Measurement. Oils are graded according to
(7) CA. Meets all automotive manufacture's
their viscosity by a series Society of Automotive
requirements for gasoline and naturally aspirated diesel
Engineers (SAE) numbers. The viscosity of the oil will
engines operated on low sulfur fuel. Widely used during
increase progressively with the SEA number. An SAE 4
the 1940's and 1950's.
oil would be very light (low viscosity) and SAE 90 oil
would be very heavy (viscosity). The viscosity of the oil
(8) CB. Meets all automotive manufacture's
used in gasoline engines generally ranges from SAE 5
requirements for gasoline and naturally aspirated diesel
(arctic use) to SAE 60 (desert use). It should be noted
engines operated on high sulfur fuel, introduced in 1949.
that the SAE number of the oil has nothing to do with the
quality of the oil. The viscoity number of the oil is
(9) CC. Meets all automotive manufacture's
determined by heating the oil to a predetermined
requirements for lightly supercharged diesel and heavy
temperature and allowing it to flow through a precisely
duty gasoline engines, introduced in 1961.
sized orifice while measuring the rate of flow. The faster
an oil flows, the lower the viscosity. The testing device is
(10) CD. Meets all automotive manufacture's
called a viscosimeter. Any oil that meets SAE low
requirements for moderately supercharged diesel
temperature requirements will be followed by the letter
engines, introduced in 1955.
W. An example would be SAE 10W.
8-6. VISCOSITY AND VISCOSITY MEASUREMENTS.
8-7.
Multiweight Oils.
Multiweight oils are
manufactured to be used In most climates because they
a. General. The viscoity of an oil refers to its resistance
meet the requirements of a light oil in cold temperatures
to flow. When oil is hot, it will flow more rapidly than
and of a heavy oil in hot temperatures. Their viscosity
when it is cold. In cold weather, therefore, oil should be
rating will contain two numbers.
thin (low viscosity) to permit to retain its film strength.
The ambient temperature in which a vehicle operates
An example of this would be 10W-30. An oil with a
determines feather an engine oil of high or low viscosity
viscosity rating of 10W-30 would be as thin as a 10W-
should be used. If, for example, too thin an oil were used
weight oil at 0 f(-17.7 c).
in hot weather, consumption would be high because It
would leak past the piston rings easily. The lubricating
8-8. Detergent Oils. Detergent oils contain additives
film would not be heavy enough to
that help keep the engine clean by preventing the
formation of sludge and gum. All SE and SF oils are
detergent oils.
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