I started a thread earlier on how to rebuild a Hypro d252 pump. I got all the parts from Rittenhouse, rebuilt it, then ran 40 gallons of Lesco Pre-M through it. All good. Then I mixed up 30 gallons of Barricade, Gallery and blue marking dye and all was fine but when I went to turn off the pump I noticed the oil was milky blue. Got home and took it apart and both diaphragms were ripped. Look at the pics. I used the regular diaphragm's not the teflon or other one.