And one last comment about the use of S versus C rated oils in hobby cars. The so called Service rated oils are engineered with a whole lot of 'usage' variables in mind - including short trips (with incomplete heating to less then normal operating temperatures), start-stop traffic, highway runs and an over-riding expectation that the crankcase will spend many more hours sitting with the engine off versus the hours running at optimal operating temperature - with the service interval measured by the odometer and/or a calendar. Whereas the so called Commercial rated oils are engineered around engines that are rarely shut off (delivery vehicles, cabs, cop cars, trucks etc) - with the service interval measured by an hour-meter.
A hobby car fits neither profile. But it would seem to be closer to the S than the C in terms of usage.
