[Fordestes]

15 degrees above normal cooling system temp is good! depending on ambient conditions, helps oil flow and less drag, lessens oil contamination from moisture retention etc. Ol'Henry, The oil contacts the hottest parts of the engine directly and carries away heat from these parts and retains what heat that is not extracted from it by the engine castings of which are cooled by the cooling system and ambient temps such as air circulation around the external portion of the engine oil pan etc., sometimes an external oil cooling device is necessary to stabilize oil temps depending on the application and demands placed on the engine.