I run 15W40 Rotella T diesel oil, Cheap and has zinc in it. Not the subject. Question for the forum, though, is has anybody tried Lucas oil stabilizer in either an XS400 or an XS650? The bottle says you can run 10% in a wet-sump bike like an old Yam, but I want to know if it will help with my many oil leaks and possibly quieten things down a bit. I don't have any profound engine issues; bike turns easy starts relatively easy, I just don't like all the OHC valvetrain noise that a mill with 28K will have, and I would think the Lucas would stick to the top end and protect the cam and "bearings" at startup better than even my 15W40 does. I wouldn't think more than 100-150cc at an oil change would be in order.

I wouldn't bother except to stick with the recommended lube. any messing may affect the wet clutch!

you are doing right by sticking with diesel oil, don;t add anything to it.