I have a 1998 chevy 2500 4x4 6.5 diesel pu.truck starts and seems to run normal ,maybe a little loud, i heard chevy diesels this year are louder than fords etc. blows a little white smoke at startup some times at idle not alot though ive seen gas engines w/bad head gaskets blow white smoke but alot heavier.problem is oil dipstick shows about 4 or 5 qts overful and coolant low . i drained all oil and coolant from engine and rad.new oil and filter in engine new antifreeze in rad . i ran the engine for about 15-20 minutes tops.shut it off ,checked the oil,same situation 4-5 qts over full coolant low , no real smoke while running also seemed to be oil in rad.,i dont know diesels but i thought if it was head gaskets it would miss or blow heavy white smoke.