It's been my experience that every O-200 powered 150 has "excessive oil consumption" if you keep the oil topped off! Many owners don't know that they are blowing that 6th quart overboard every flight, and that the O-200 does just fine on between the 4.5-5 quarts left in the sump.
But, I don't know "this" plane or it's history, so maybe it does need rings.
