Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Spooky connection here Ash as I read your post over on the black bomber thread this morning and thought of this subject and of opening a thread about it.Usually listed in content as ZDDP, Zinc Dialkyl Dithio Phosphate, it has some pretty unique properties and effects, especially for older engines.It's now being almost totally excluded from modern engine oils as when passed into exhaust stream it will have a destructive effect on catalytic converters and the like.Basically it floats around in engine oil and just exists without doing much until it comes under extreme mechanical pressure in situations like camshaft lobes. It typically prevents metal spalling and pickup (the destruction of machined surfaces) when the shear capability of the oil is exceeded and can have a hugely important function in preventing wear starting. I'm a fully paid up, anorak wearing advocate of ZDDP in oils as I look after a number of engines that would be considered in need of specific consideration in this regard.
I've got to page 7 of Jensen's posting, some very interesting additions coming in there.Both you and Mike in an early post reference Bryan's view on oil for these old bikes, I think he's right on the ball for getting that spec to people asking the, what oil should I be using question. For people wanting a straight up recommendation it couldn't be more simple, and those oils mostly would have a zinc component as they have no attachment to current engines which effectively have their oil components legislated via emissions regs etc.I think here we should look at if anything better is available and if so, why. Hopefully it may even get some more insightful contributions to debate.I'll get off and read the rest of the Jensen case study to see where he got.