A 100 Dodge Van White Smoke

The question is if the smoke is water/coolant, or oil. Oil typically has a bit of a blueish tinge to it. Place a cool mirror up behind the exhaust and see if moisture condenses on it. If so, it is water/coolant. Anti-freeze also will have a sweet odor to it. If it is that much water/coolant being lost, you will see the coolant level dropping over time keep and eye on the overflow tank level, and also check the coolant in the top of the rad after it has cooled overnight to see if the level is dropping. Ditto for the oil on the dipstick.