The Sthil and the Flymo will both use 50:1 on proper synthetic 2-stroke oil. If you use Sthil oil, it states 50:1 on the bottle. You can use this in ALL 2-strokes - no matter what it says (if anything) on the engine.
I assume the Honda is a 4-stroke - if it has the 4-mix engine (it will be prominantly marked as such if so, it uses the same mix as the 2-strokes. If not, then use SAE30 mower oil in the sump. The V-twin shoud have SAE30 mower oil.
phil_saunders(a)bigfoot.com
Phil Saunders, June 2009