It's been determined that MC 5-20 is part synthetic, and a great oil. My question is if the new MC 5-30 is the same type of mixture, only in a slightly higher weight. The bottle says it's synthetic [part], but does it mean the same thing as the 5-20? I'm not sure if it's a legal/sneaky thing, or if it's the same high quality as the 5-20. I'm not sure from checking posts here - anybody know for sure?