I looked under my car today and noticed a HUUUUGEEEEE oil mark around the oil pan and under the tranny. I'll be taking a look at it this weekend, but is there maybe anything I should specifically look for? I do the oil changes every 3k, so IDK what the problem might be. Car is a '00 EJ6 sedan.

 

Take a pic and post it. But its probably either the rear main seal (in between the trans and engine), oil pan gasket, or leaking down from the top somewhere.

 

Is it engine oil or transmission fluid?

For an engine oil leak, start your search at the top of the engine (distributor, valve cover) and then work your way to the bottom (oil pan, rear seal).

 

I am willing to bet rear main seal, esp if it on the side of the oil pan.