How can I tell if my oil pan gasket is leaking?

[belfert]

I have/had two oil leaks on the driver side of my Series 60 engine.  Anyhow, I have oil all along the oil pan gasket and below that on the oil pan.  Is this just oil that has migrated along the gasket from my other leaks, or is this a sign my oil pan gasket is leaking?  My oil pan has at least a 1/8" thick layer of oil and dirt along the entire bottom side.  I do know that my rear main seal leaks, but not enough to spend thousands pulling the engine and repairing it.

My oil leaks are minor enough to not even be noticeable on the dip stick.  I can go 4,000 miles and the oil level seems to be right where it started at.

On another note, do I need to drain and change my oil if I work on the oil cooler on my Series 60?  Should I at least replace the filters?

[pipopak]

Well, the first step would be to clean up the mess and take a good look. If it's the pan maybe tightening it a little bit will do.