Clean the entire engine making sure you get the top, front and bottom with some kind of degreaser cleaner. Make sure you get it clean! Dry it off really well!
When you have an oil leak, as you drive down the road, between the fan and airflow, it pushes any leaking fluid from the front to the rear of the engine. Once the engine is completely clean and dry, take it for a test drive. Once you return and park it overnight, if you see oil on the ground? Locate the oil leak by starting from the front of the engine and working toward the back. Chances are you will need to be looking at the engine from underneath to spot the leak. Now that you've located the area closest to the front of the engine where oil residual is coming from. With the engine running at an idle, you may be able to see exactly where the oil is weeping from.
Ive found many leaks like this. Its a pain but it works. This way you can be sure if what you've been told where your leaks are is true! Hope this helps?