Well I finally looked at real info about oil (engineering info about what goes into the making of different oils). Must admit I had much wrong. The W is just the designation of a testing proceedure (as in 20W-40). There was a heck of a lot more, but there were some things said that would be important to me. 1) you want about 10 lbs. of pressure for every 1000 rpm under your own riding conditions. So 4,000 rpm should give about 40lbs. pressure. That's according to many manufacturers. But I don't know what Norton says about that. 2) ALL oils are too thick on start up -- they violate the 10 lbs./1000rpm rule. So you want maybe a 0W-50 (synthetics go that low) or 0W-40 or whatever. Even 0W will be too thick on start-up at 75°F. But it thins to the correct viscosity much faster than, say, even 20W 50. Because the oil is always too thick on start-up it doesn't flow fast enough and flow, not pressure, keeps metal separated. And that's why almost all wear occurs on start-up. So the pressure gives you a means to tell if you really need 50 grade on the high end.-- maybe higher, maybe lower -- according to riding style and the oil pressure guage. 3) synthetics start at the high grade, but standard petroleum based starts at the low grade and achieves the high value with extenders which break down. When it degrades viscosity drops (gets thinner when hot) and it can no longer stay at the necessary 10lbs/1000rpm to acheive proper flow. It also gets a little thicker on the low end when cold and that's far worse. 4) Again, it's the flow not the pressure that keeps metal separated. There was a lot more, but maybe I could find it in the forums back pages. I'll look some more. Meanwhile I think it would really pay me to install a good oil pressure guage. Anyone know the right connection for that? Just this one thing more. All I have written about this comes from reading, reading publications from the oil manufacturers and such car makers as Ferarri, etc. I have yet to find anything from the aircooled engine people, though modern Norton, Deutz and Porche and even Harley would be a good place for me to start. And, yes, if this is all on our back pages it really is my fault for not finding it yet it. Mea Culpa.