Volvo: 1978 Volvo 242 DL Water in oil, blown head gasket, piston rings

Question
My Son ran it out of oil, starts but stalls out, white sludge in oil.
Piston Rings?
Head gasket?
Does a novice repair Dad attempt repair?

Answer
Michael.
It sounds like a warped head or blown head gasket. If the oil is engine oil then take a compression test and cylinder leakage test if you find one or more of the cylinders leaking, the head will have to be removed and sent to the machine shop to be checked for warpage and cracks.
Are you a handy sort of person and have the basic mechanical skills along with a healthy dose of patience? If you are Mike go for it.