I've been following your thread since the beginning. I did the same procedure on our '98 Bonneville, so I'm familiar with what you did and with some of the problems.
I'm desperately trying to think of scenarios where this is not a blown head gasket or a corrosion in the block between oil and coolant passages (both of which seem to be somewhat rare problems in the 3800 engine [in my limited forum readings] compared to intake manifold problems[which are almost inevitable]).
Is it possible that when you did your UIM/LIM work on Thursday, that you didn't drain the radiator sufficiently? The timing of the sudden drainage of your coolant reservoir and the overflow into your oil pan seems to coincide with your intake manifold work.
With that said, maybe this is what'* happened:
1. You bought the car recently and noticed the milky oil and the white exhaust smoke due to coolant getting into the combustion chamber(*) by some means. Let'* say this was due to a trashed uim/lim system in some way.
You had not experienced any significant coolant loss up to this point. (Wednesday the fourth) Nor any significant oil loss (or gain!)
2. On Thursday the fifth, you did the uim/lim procedure. You mentioned that you spilled some coolant into the area below the LIM when trying to pull it out. Suppose that you also were accidentally draining (unbeknownst to you) coolant from the radiator and coolant reservoir into your engine block at the same time. (I'm not trying to be critical, just trying to think up a happy ending for this story
)(and we all[certainly me, anyway
] make mistakes during one of these procedures).
3. Ok, on Friday (I have to guess at the dates, but you would know better), you notice all of a sudden you've lost alot of coolant from the reservoir, your oil level is sky high and your exhaust is still expelling coolant. Let'* say you didn't change the oil after the manifold work. Now
, the problem is different. It'* because of the accidental introduction of coolant into the block (and subsequently into the oil pan) during the manifold procedure.
Sounds zany? Think about it. I really hope I'm right (I sure like '98s
The cure would be one more oil change.
Ok, a lot of assumptions, but if there'* anything to what I've presented, it sure could save you a lot of work.
(edited by me a little later: Is there anything else you can think of that may have occurred during assembly? A pinched or defective gasket? Something loosened up? Any head scratching about gaskets not properly matching the manifold holes? Who knows -- maybe you've run into a corollary of the "Buttermore Principle" (like installing brand new, but defective plug cables and you don't catch it for days or weeks) -- you do the right thing, and somehow it (as well as all of your assumptions) comes out wrong :( )