IMHO, the OS46 SF engines are among the best OS engines ever. I have several 46SF engines, ringed and non-ringed, and have never experienced any problem with liner peeling. That's a problem that occured with later OS engines.
18% oil is O.K. as long as you don't run it lean. I use 15% oil in my fuel and have had no problems whatsoever with wear. One of my SF:s has been run for more than 300 hours in different aircraft and the only thing I have ever changed is a rear bearing.

One problem that some people experienced was that the engine didn't run well with muffler pressure. I run my engines with no muffler pressure and it works great. Apparently it had something to do with the position of the muffler pressure nipple position relative to the baffle inside the muffler.

Good luck with your SF! It will be with you for a long time if you take good care of it.

/Red B.