Since viscosity modifiers supposedly get chewed up worse by the higher speeds in bike gearboxes, wouldn't an oil like that (with a wider range than required) suffer more than a 10W40?
Always used semi synth Vauxhall car oil in my bikes cos I get it almost free. Used it in GPZ9, did about 15k on that, CBR Thou, took that from 25k to 67k, and my current CBR Thou has close on 50k on it. Never had problems.There was also a bloke in 'Ride' magazine (i think) a few years back who was a courier. He did 440,000 miles on one of his VFR800s and used the cheapest car oil he could find. Changed it every week and had no problems either.
Easy Rider 13, what have you done? I saw your post and thought take cover. It is a much discussed subject, as you can now tell. Something the right spec, semi-synth, nothing fancy, will do the job.Cheers Dave
Hope you're having a happy birthday, btw and I hope someone bought you four litres of expensive bike oil.