Hi!
Your'e right! Over here in Europe most people do run all their engines on just 10-15% oil...and all synthetich at that!
No one in our club (Around 100 members) does use castor oil anymore and this is not a new "thing" in Europe. We have run our engines this way for decades. So please don't say anymore that 20% castor oil is necessary in a modern engine...becasue it isn't!
32 years in this wonderful hobby!
Regards!
Jan Karlsson
Sweden