Volvo: S40 2000 : Oil Leak, seal leaks, car axle

Question
Hi. I have oil leaking under the engine, but only while it runs. And my mechanic could not find where the leak is coming from. May I ask how is that possible?  Thanks.

Answer
Boon,
Your shop is not taking time to clean and look for the leak. That being the case, take the car to a shop that KNOWS the Volvo's and have them look at the car. Axle seals leak trans fluid, rear engine oil seal leaks oil, front trans pump seal leaks trans fluid, steering rack leaks P/S fluid. Time for a good shop to so some inspecting.