antifreeze in oil

How much water was there? Was it clear or pink ? Is there any milky substance under the oil fill cap? The most common (reached epidemic status) problem that allows coolant into oil is the lower intake gaskets, if your technician replaces them then spring for and insist upon the updated gasket sets, Fel-Pro calls them problem solvers. This problem if not corrected immediately will destroy your engine. I can't stress immediately enough. Good luck

Coolant in the oil typically means you have an internal engine coolant leak, causing coolant to get into the lubrication system. This would be typical of a failed cylinder head gasket, or cracked cylinder head. Was the oil milky? Often an intermix situation results in brownish milky oil coming out. Check your coolant reservoir for an exhaust odor also, as this tells you that exhaust gases are also getting into your cooling system...also a good clue telling you of a head problem.

BAD DO-DO. It would appear that you have a coolant / oil intermix. DO NOT CONTINUE TO RUN THE ENGINE!!! Find the source of the leak and repair it. Then flush the oil system. Most likely cause is blown intake manifold gasket. Other possibilities is head cracked or head gasket leak.

Is it possible that your radiator has a crack in the oil coolant reservoir on the side? I would start simple/cheap before going into the engine itself.