<div class="section abstract"><div class="htmlview paragraph">INVESTIGATIONS of the lubrication of both reciprocating and turbojet aircraft engines are reported here.</div><div class="htmlview paragraph">For reciprocating engines, the major goal has been to do away with the necessity of applying large quantities of preheated air to start the engines. This is being done through the development of appropriate equipment and improvement of starting techniques.</div><div class="htmlview paragraph">The problem has not been so severe for turbojet engines. In fact, oils of low pour point plus the adoption of the closed-circuit oil system are expected to eliminate any need for heating the lubrication systems of jet engines.</div></div>