What causes oil to blow out the dipstick on a 5.7 lt1 engine?

A bad PCV valve can cause excessive oil leakage and consumption. A PCV valve helps relieve pressure in the crankcase. If the PCV valve malfunctions, crankcase pressures can increase, forcing oil through seals and gaskets. check the vacuum hoses to the pcv and the other vacuum lines also. it can be numerous things wrong! good answer also a over filled crankcase, a bad oring on dipstic, also worn pistons and or rings can cause blowby where your compession gets by the piston and rings and pressurizes the crank case causing the oil to escape the easiest way it can.make sure you have good vaccum pull at pcv valve a cloggeg hose or fitting will cause crankcase pressure