What would cause a 1987 Vw Cabrio to lose all the oil from the engine suddenly?

I just bought a car and the guy said he was driving down the road and all of a sudden all the oil leaked out of the engine. Luckily they stopped driving it. I got a really good deal on it so I would like to fix it up as I have always wanted one and here was my only chance to get one under $600.00.What would cause a 1987 Vw Cabrio to lose all the oil from the engine suddenly?Loose oil filter, loose oil drain plug, cracked oil pan, cracked engine block. Loose or missing drain plug is a cheap fix as is a loose filter, oil pan can get pricey and engine block even more so.What would cause a 1987 Vw Cabrio to lose all the oil from the engine suddenly?well evidently there must be an oil leak somewhere. Loose pan, seals, could be a number of places. If the engine cosumes more oil than it should, the piston rings and/or valveguides are bad