No don't put it in your Vincent, we were advised not to use it when I had my Lawnmower business, we saw it used on a revolving pressure machine that spun and compressed metal to metal until seizure, ironically straight 30 grade was the best, yours and other expensive multigrade oils failed/seized much sooner, other opinions welcome but that's what we saw, and, Briggs and Stratton were the biggest maker in the world of engines then and they said 30g too, that said I use 20/50 classic and or 30 or 40 grade myself because I was given it.
Lovely 30 mile ride out tonight at our old bikes at the old George and after, so nice to get out, 108 bikes there tonight, only one Vincent tonight, my Prince, always appreciated locally because only about 10 miles from where they were made ! Kerry.