Pope has it covered on this one. A lot of oil brands tend to lean towards a chlorine base add pack. It's like taking your wife's bleach bottle and dumping in your system. Chlorine is highly oxidizing and it's moisture content always comes to the top of the system (highset point of engine). Bad for bearings and wear reduction. It does happen to be friction reductive for a short period of time. Heat (by running engine under load) will get rid of the moisture at the valve cover but if it's chlorine caused........ya outa see what it's doing to your bottom end, bearings and stuff. double check crankcase ventilation for good draw. Whether you run standard PCV or evacuation pump.