Cadillac 1937 LaSalle VVI Information page 27

Engine Oil Recommendations
During summer weather, engine oil can be selected
upon the basis of the type of driving. S.A.E. 30 oils should
be used for driving at moderate speeds. If high speed driving
is the rule, however, heavy duty oils of S.A.E. 40 or 50 grade
will provide better oil mileage than will the lighter grades.
During cold weather, selection should be based primar-
ily upon easy starting characteristics, which depend upon the
viscosity (fluidity) of the oil. The table on the next page
gives the viscosity specifications of the various grades of oil,
while the diagram below shows the temperature ranges
within which each grade can be relied upon to provide easy
starting and satisfactory lubrication.
When the crankcase is drained and refilled, the oil should
be selected, not
on the basis of
the existing tem-
perature at the
time of change,
but on the anti-
cipated mini-
mum tempera-
ture for the per-
iod during which
the oil is to be
used. Unless the
Page 44
engine oil is selected on the basis of the viscosity at the pre-
vailing minimum winter temperature, difficulty in starting
will be experienced at each sudden drop' in temperature.
Only 20-W and 10-W oils are suitable for use when weather
conditions are below 30°F. The reason for this is shown in
the chart below, which indicates that the viscosity limits of
20-W and 10-W oils are taken at a temperature of 0°F.,
whereas those of S.A.E. 20, 30 and 40, all of which are
summer grade oils, are taken at a temperature of 130°F.
Heavy duty oils of S.A.E. 40 or 50 may be used in cold
weather if the car is kept in a heated garage or if the heavy
duty oil has a cold viscosity sufficiently low to insure against
hard starting. Otherwise, the oils specified in the chart must
be used and, in
cases of p r o -
longed driving
at high speeds,
the oil level
checked more
frequently as
the rate of con-
sumption will be
higher than at
moderate speeds.
Page 45