Robert, I dumped the fairly new Brad Penn 10w40 I had in Whitecloud after reading the Rat's ramblings.
I put Mobile 1 synthetic, 5w30 and he (Whitecloud's a guy) loves it! I've always been concerned about start-up and cold-start-up oiling as a large amount of wear occurs then. I think more than ZDDP levels, the shear-strength of the oil film protects parts, especially on start-up when most engines have no oil pressure and residual oil is what protects the wear-surfaces.
Heck, if thin oil is good enough for Gene Berg, it's good enough for me!
Kath and I returned home last night from a day with friends in Arroyo Grande. We left the south county just before dark, 4:45 pm and when we hit the grade (first time with Pat's new engine) I kept a steady throttle at 3K rpms, passed a few cars on the way up and had so much headroom, maybe another 30% left and the Cuesta Grade is a litmus test of all tests, especially air-cooled cars: 3 1/2 miles of straight-up grade, so stoked!