fd56ec0a_MOTOR_OIL_GUIDE__Use___Definition
[API Symbol] CA (obsolete) (Light Duty Diesel Engine Service) [Use & Definition] 
Service typical of diesel engines operated in mild to moderate duty with high quality fuels and occasionally has Included gasoline engines in mild service. Oils designed for this service provide protection from bearing corrosion and from ring belt deposits in some naturally aspirated diesel engines when using fuels of such quality that they impose no unusual requirements for wear and deposit protection. They were widely used in the late 1940's and 1950's but should not be used in any engine unless specifically recommended by the equipment manufacturer.
MOTOR OIL GUIDE
Use & Definition