JBurry- Thanks that makes sense now that I think about how they worded it in the manual w/reference to the ring.

I asked Hobbico about castor oil this is how it went:

Me:Hello I just purchased an OS 46AX, and have a question regarding lubrication. I have fuel that is 15% nitromethane, and 18% synthetic
oil. I have read in many places that castor oil is the best for the engine, especially during break-in. I have a brand new bottle of
castor oil from the pharmacy, and am wondering if I should add some to the fuel. If I were to add the whole bottle to the fuel I have, it
would create a blend that is 22.8% oil (30/70 castor to synthetic) and 14.1% nitromethane.

Do you suggest I use the castor oil for the break-in period, or just
use the fuel with synthetic lubricant?

Hobbico (OS):
Joe,
Thank you for your recent e-mail. It is a good idea to use a castor/synthetic blend but it's not required. If you add that much castor it will allow your engine to run a lot cooler but you will loose some performance. If you have a lot of experience running engines then you would probably be ok to run just synthetic but if you don't, running castor will help prevent overheating.