TM 10-3930-671-24 IMPORTANT READ THESE INSTRUCTIONS CAREFULLY All points of operation and maintenance have been covered as carefully as possible but, if further information is required, send inquiries to the factory for prompt attention. When  writing  to  the  factory,  ALWAYS  GIVE  THE  MODEL,  SPECIFICATION,  AND  SERIAL  NUMBER  of  the  engine referred to. Starting & Operating New Engines Careful breaking-in of a new engine will greatly increase its life and result in trouble-free operation.  A factory test is not sufficient to establish the polished bearing surfaces, which are so necessary to the proper performance and long life of an engine.  These can only be obtained by running a new engine carefully and under reduced loads for a short time. • Be sure the engine is filled to the proper level with a good quality engine oil. • For proper procedures to follow when breaking-in a new engine, see "Testing Rebuilt Engine". The various bearing surfaces in a new engine have not been glazed, as they will be with continued operation, and it is in this period of "running in" that special care must be exercised; otherwise, the highly desired glaze will never be obtained. A new bearing surface that has once been damaged by carelessness will be ruined forever. F-129