This one comes from Russia. Nearly 3 years ago I did complete engine overhaul to my V8/PT/91. I got rings from Mahle - the original manufacturer of pistons and rings for this engine. I had to buy new pistons as well! The block required reboring for bigger diameter. Mahle still retail these parts, although they are hard to get. It cost me a fortune! I had the same problem as you - the 3rd cylinder was comletely wasted and oil was just running through it. After overhaul I only add 1/2-3/4 liter of oil every 15000 km between oilchange. maquinista@mail.ru