I HAVE A 99 YUKON AND I PUT NEW HEADS IN IT BUT NOW THAT EVERY THING IS PUT TOGETHER WHEN I PUT WATER IN RADIATOR IT GOES STRAIGHT TO OIL PAN. WHATS CAUSING IT
the fuel injectors are leaking.
stop putting water in the oil fill.
There may be a damaged head gasket (improperly installed) or perhaps a warped head allowing coolant to breach the gasket.