Yes I am, & a 20yo (probably high mileage) 1600 detuned twin cam isnt what I`d call sophisticated. There will be ring & bearing wear & even when new they wouldnt have been particulary tight, add to that the fact the seals & gaskets are now going to be `loose` & will be more prone to leaking the thinner oil & thats another good reason not to use an oil thats too thin.
If he puts a thin oil in, his consumptions going to go right up, his power will go down, he`ll start smoking & the oil pumps going to struggle to give good pressure. Not recomended.
My prides got nothing to do with it, the gentleman asked a question & I answered, thats all.
