I recently purchased a 1999 Cambell Hausfeld VT619503AJ 60gal air compressor from a friend of a friend. I installed new cylinders and rings, replaced all gaskets and seals, and put a solberg air filter (silencer) rated for 12cfm. I also cleaned all the grease and oil off of the unit and repainted it. I continue to get oil in the tank and quite a bit. I put exactly 12oz of royal purple compressor oil in the pump. I continue to get the oil/ water mix out of the drain every time I use the compressor. Any ideas on what else could be causing the problem. I took it all apart again to check the rings and make sure everything was where it was supposed to be, etc. There is some burnt oil on the valve plate which I cleaned off and put it all back together. Does anyone have any suggestions on what could be happening here? The only two things that I see could possible be going on would be that the royal purple compressor oil is too thin and making it past the rings? But I have searched high and low for others having this problem but haven't found anything. I will probably put in the ch oil and see if that makes a difference because that's the cheapest route. Only other thing I could see is that maybe the solberg air filter has too high of a resistance and is causing some kind of back pressure, but I continue get the oil in the tank even with it removed. Any suggestions on what else to try would be greatly appreciated. I hate to sink any more $$$ into this thing as I probably could have replaced the pump for less money and definately less time than this trial and error has gotten me so far.