2000 International Truck s oil in the cooling system and wat

blown head gasket
cracked head
cracked block
leak in the water over oil cooler

dont run it this way. you'll kill the engine.

The most common cause that we've seen for coolant in the oil is from leaking piston liner sleeve o-rings, also the other common cause for coolant in the oil is usually from your oil cooler.
To check for liner o-ring leak causing water in oil we recommend removing oil pan fill cooling sys. with water if low and pressure test cooling sys. at coolant tank with pressure tester and look for coolant leaking down oil pan.