Originally Posted by
bogbeagle
As I understand things, some of the Klotz oils contain a percentage of Castor.
Castor, being gummy, is bad news for the delicate regulator/Non-return valve of some YS engines.
I mix 1% castor in my YS fuel. It doesn't cause any problems with the reg. The only thing it does, is cause a bit of staining on the engine.