1938 LaSalle Production - GM Heritage Center

Under normal driving conditions, draining the
crankcase and replacing with fresh oil every 2000 to
3000 miles is recommended. Under adverse driving
conditions, it may become necessary to drain the crank*
case oil more frequently.
Short runs in cold weather do not permit thorough warming
up of the engine, and water may accumulate in the crankcase
from condensation of moisture produced by burning fuel.
Water in the crankcase may freeze and interfere with proper
oil circulation. It also promotes rusting and may cause
clogging of oil screens and passages. Under normal driving
conditions this water is removed by the crankcase ventilator,
but if water accumulates on short runs it should be removed
by draining crankcase as frequently as may be required.
During winter months, light or low viscosity oils are
required to obtain easy starting. The crankcase should,
therefore, be drained at the beginning of winter and refilled
with oil of the proper viscosity for winter use. After continuous
hard driving, these light oils may thicken and cause
hard starting. Thus, although a drainage period of 2000
miles may be desirable for cars subjected to high speed
driving, under very severe conditions more frequent draining
may be required to prevent hard starting due to thickened oil.
It is advisable to drain the crankcase only after the engine
has reached normal operating temperature. The benefit of
draining is, to a large extent, lost if crankcase is drained when
engine is cold, as some suspended foreign matter will cling to
the sides of the oil pan and will not drain out readily with
slower moving cold oil.
Whenever the crankcase oil is changed, the copper gauze
in the engine oil fillercap, which is also the air intake for
the crankcase ventilating system, should be cleaned in gasoline
and dipped in engine oil.
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