Mixing oils
Oilman, a quick question for you. At the weekend we were on a bike run to the west coast of Scotland and one of the guys oil lights came on (R1) indicating low oil level. We could not get m/cycle oil anywhere and he decided to do a 70 mile detour to go to a bike shop in Inverness to get the correct m/cycle oil. I have read somewhere that m/cycle oils have longer chain ester molecules compared to car oils to help resist shearing due to being the gearbox lubricant as well (what about the old minis?

) Would a good car oil, semi or fully, have sufficed to finish the run, then change it when he got home, or was he right going to get the correct oil.
Basically what I am asking is, can you (in an emergency) safely use car oil in a bike engine, or must you use bike specific oil, is this another urban myth?
Sorry for the thread hijack
Cheers
Ian