Just wanted to add this.... I had a leak that was darn near impossible to track. It was leaking drop around the AC compressor like the original poster mentioned. As it turned out, the "mechanic" that worked on my driver side head, had the whole head apart, and replaced the front cam seal with a generic seal instead of a proper OEM seal! So what happened was the generic seal was ever so slightly undersized and popped out of the channel it is supposed to fit into. This allowed oil to leak out where the cam exits out the front of the head. This is of course covered by the timing belt cover. So the oil leaked from the cam, behind the cover, down the front of the block, and pooled at the bottom inside of the timing belt cover, and then " leaked" by the "AC compressor" making me think it was the oil pan. Just something I hope helps others when looking for a mysterious leak that can't be found.