1. Aircraft engines are largely cooled by the flow of oil through the lubrication system.

2. An excessively low oil level will prevent the oil from cooling adequately and result in an abnormally high engine oil temperature.

3. Exhaust manifold type heating systems are used as a heat source for the cabin and carburetor. The risks of operating an aircraft with a defective exhaust heating system include carbon monoxide poisoning, a decrease in engine performance, and an increased potential for fire. Because of these risks, the exhaust manifold should be periodically inspected.