locating coolant leak

I have been trying to trace a coolant leak, but have had no success. I noticed the coolant dripping from the oil pan, then i traced it up from there. I went up the left side of the engine. The only thing over there cooling related is the thermostat and the bi-pass lines. Neither of which are leaking. I checked the oil and i don't notice any water. I'm not sure how the coolant passages run through the engine, but i'm guessing that i have a failing head gasket. Should i look at anything else before i start taking things off the engine? I have a 97 Century and the leak is not really bad. I have to add coolant once every 3 to 4 weeks. Would a sealant additive help? I should also mention that i have recently had a thermostat problem and the engine coolant temperature needle did indicate very hot several times (that i noticed) before i replaced the thermostat. Not sure if this may have any bearing on the problem or not.

check around where the intake manifold meets the heads, and the engine block

Yes, that is the area it is coming from, though it is difficult to pinpoint. I've been trying to search using an inspection mirror, but there is just not enough room.

I've done it, not incredibly hard, just long, and time consuming

I am sure that your 3.1L engine intake gaskets are leaking. It is a common problem on this engine GM has issued revised intake gaskets to cure this problem.

Ok, i will replace the gaskets. Thanks for the help.

New gaskets in place and no more leaking. You are right, it did take a lot of time, but wasn't difficult. Thanks again.