Engine Oil Leak-My Engine Leaks oil- New to Boards

[Saab Let]

My 2004 Saab 9-3 2.0 leaks oil. This is not an obvious leak. I suspect oil cooler or sensor switch for oil near filter. One mechanic said possible rear main seal on engine crank.
It leaks more on longer runs and not so obvious on short runs.

It has 97,000 miles and still runs good. Even if the find a leak can someone fix it and still have any parts to repair it with?

[Saab Let]

We took on a road trip with the Saab and noticed oil was leaking on the ground underneath the car engine area. This one dealership service manager for Saab where we stopped said it maybe a rear main seal leaking on the main crank. All they did was change the oil. After that dealership changed the oil we drove the car to our destination home many many miles away. The oil leak was thought to have gone away. However I recently had the oil changed. We drove it on a short trip. The following morning I noticed a puddle of oil on the concert about a 1/2-1 cup of oil. Since then it only leaks at a few drops at a time.