My 72 has the same problem. I thought it was getting better with time, chrome cylinder beaking in slowly, but now I have more than 10 gallons on the engine.

I tried to solve the mess by connecting the vent to muffler. See this pic http://www20.tok2.com/home/rc/data2/...22/html/17.htm

The problem with this setup was that vacuum sucked the valve train almost dry from oil. I checked it after 3-4 flights. In the end I have learned to live with the oil mess.

I was also concerned about having a problem with the ring but I doubt it. When comparing to the rpm figures I have seen here, my 72 seems to be on the strong side. It also starts and idles pefectly.

What are the sings of a bad ring -- nice to know If I choose to dismantle the engine.