My thinking is that if the oil filter is doing its job and the oil looks clean as a whistle after 350 miles or so, then the oil probably does not need to be changed. If there isn't anything clinging to the sump plug then chances are not much swarf has been generated. Don't know much about S & S but I'm sure they're well engineered and made.
A high reading of 65 C is extremely low isn't it? The oil temperature on modern engines would be about 90 - 105 C without any problems and that's on a thinner oil. Where are you measuring the temperature - in the engine or in the tank? I would expect the temperature in the tank to vary a lot more than in the engine as there is clearly some temperature management going on (eg. shutting down ignition at higher temperatures).
I'm not questioning what experts are saying about needing all these oil changes, but I can't say I understand why they are necessary and the cost and waste of all this oil is a bit daft if it's essentially about being cautious.
What did Charles M do on his recent 3000 miles dash across US. I'm sure he didn't change the oil?
Oddly enough, I would expect the S & S engine to work with pretty much any oil given there is such a lot of it, and it is not exactly dealing with high revs, much power, torque, weight or revs. Even piston speeds are not especially high given the low rev limit.
Having said that, I have no real expertise in this field, just a bit surprised. If it were a bike engine revving to 16,000 rpm and developing 150 bhp per litre I would take a different view!!
