Here's a fun week end project! making oil leak finding fun.
Wash (Steam clean) the engine bay (or whole car) re grease all your nipples

then go for a spirited drive to the supermarket. If you cant find the leak on investigation of your squeaky clean engine, buy a bottle of baby powder (magnesium silicate) and powder your engine. Drive home and inspect your engine, if you still cant find the oil leak, drive back to the supermarket and ask for a refund as you're not 100% satisfied!
On Monday, they'll all think you're made at work.
THIS IS NOT for the HOW TO section!