Interesting comments, guys, and I don't have a problem with the use of synthetics on modern engines with clearances down in the fractions of a thousandth, and alloys that have virtually no thermal expansion. It's just not worthwhile nor wise to run that type of oil in a 50+ year old engine designed for 30 weight mineral oil. The very first use of synthetic oil that I'm aware of was on jet turbine engines, and the dead-end type lubrication with no return to a central sump meant that the oil was eventually consumed by the engine. A free-flowing lubricant that burned in the exhaust stream with little or no ash was needed, and synthesized oils based from vegetable products were eventually developed. These oils were later fortified with additives to make them compatible with reciprocating engines, and suitable for recirculating oil systems. I'm still partial to a high quality, high-detergent mineral oil with a straight viscosity for 1940's or 50's designed engines. Regular oil changes and reasonably good filtering will still be of more advantage to these engines than some trick-compound oil, at least in my decidedly biased opinion!
Jerry
