Chrysler Plymouth 1962 Owner's Manual page 38

SHORT TRIPS AND SLOW SPEEDS
(especially in
cold weather) to the store, school, etc., and home again
before the engine warms up causes harmful condensation
and sludge formation. Oil changes as frequent as every
500 miles, or not longer than 2 months, are recommended.
DUST AND SAND cause abrasives to enter the engine
and damage moving parts. Frequent use of dusty roads
or driving in dusty or sandy geographic areas demands
frequent oil changes. At the end of a week's vacation in
dusty or sandy areas, an oil change is recommended.
Driving through a dust storm is particularly harmful if
the oil is not changed as soon as the dust storm has sub-
sided. Air cleaner and crankcase ventilating intake-cap
should also be cleaned frequently.
Any authorized dealer's Service Manager knows the
frequency that oil changes are required in his area.
Follow his advice for yo ur particular needs.