Re: UnKnown LEAK in Engine
I hate to say this, but there's probably a crack somewhere either in the heads or the block. The same exact thing happened to my truck when I first got it. Mechanic told me it was the head gasket because there was an external coolant leak from the gasket area and the oil had water in it. When I got the heads off everything looked normal and the gaskets were ok so I took the heads to a machine shop to get em cleaned and inspected. Turned out that both of them were cracked. This is likely to be your problem. Not many other things it could be.
Hopefully its nothin too major though like a cracked block. I just wish I had got the vortec heads while the old ones needed replacing, but I wasn't sure if they would work on my TBI engine.