Porsche 944 S2 Owner's Manual page 61

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Examples of approved
viscosily
classes
lf
your vehicle
is used
in stop-and-go traffic
in
winter,
the
engine
will
not always reach its
optimum operating temperature. Condensa-
tion from
products of
combustion may ac-
cumulate in the oil.
lt
is
therelore
advisable
to
change
the
oil in
spring so that your
engine
once again has
a
100%
efficient
engine oil.
Engine
oil
perlormance class
Engine
oil is
not
only a
lubricant,
but
also
serves
to
keep
the enqine clean,
to
neutra-
lize
the dirt which
penetrates into
the engine
through combustion and
to protect the
en-
gine
against corrosion.
To
perform
these
functions, the
oil
contains additives which
have been specially developed
for
these
Iunctions.
So-called
mineral
oils are
pro-
duced directly
from
crude
oil. The oils
can
be
further
refined (hydrocrack oils) or totally
converted
through
a
number
oI
chemical
processes (synthetic oils). These
oils
are
structurally more
eflicient and require
fewer
additives than
simple mineral
oils.
The efliciency
of an oil is
expressed,
lor
example,
by the API classifications which
are
divided into
categories
"S" and "C".
The
degrees
of quality are
expressed by final
letters
in
alphabetical
order: The
require-
ments
lor
PORSCHE
engines are API class
SE/CC
to
SF/CD.
Viscosily
Engine
oil
is viscous when cold, and thin-
bodied when warm. The viscosity
of
an
oil
is
expressed by its SAE class. For
cold
viscos_
ity
(measured
at
temperatures
below
0'C)
the SAE class
is given as a number and the
letter
"W"
(as
in winter);
for
hot viscosity
(measured at 100"C) the SAE class
is given
only
as
a number.
The viscosity
oI an
oil
is, therefore,
always
the same
iI it
has
the same number
of
an
SAE class.
E.
g.:
A
10 W-30
oil and a
10
W-40
oil
have
the same
viscosity when cold (below
0"C);
when hot (at 100'C) the
oil with
the number 30
is
thinner than the oil
with the
number 40.
Single-grade/mulligrade
oils
Oils with
two
viscosities
are called
multi-
grade oils; oils with only one viscosity are
termed single-grade oils.
Single-grade
oils
can
only be used
for
the
narrow
temperature range identified
by
their
SAE
number; multigrade
oils
cover a
wider
temperature range (see chart).
Fuel efficient
oils
Fuel
eflicient oils
require low viscosity at low
temperatures
and high thermal
stability
at
high temperatures.
As
high-performance
oils, these
oils
are
manufactured
only as synthetic
or
hydro-
crack oils at present.
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Engine Oils
Use
only
engine
oils which meet the specifi-
cations designated
by
PORSCHE. Your
Porsche dealer
will be glad
to
advise you on
the correcl type ot
oil
for
your
engine.
These
oils
can be intermixed. Since,
how-
ever,
each brand of
oil
has a special compo-
sition, you should, if possible,
use
the
same
oil
brand if
it
becomes necessary
to top
up
between
oil
changes.
PORSCHE engrnes
have long intervals
between
oil
changes.
You can make best use
ot
these long oil
change
intervals
by
using multigrade oils or
multigrade fuel efficient oils since these
are
largely independent of seasonal fluctuations
in temperature.
58
Look
Ior
this
label
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