Several years ago I had the valve cover replaced because of oil on the oil pan. Had the oil changed yesterday and there was oil on the oil pan. Dealer put in some
"dye" and told me to bring car back in several months. Special lite might identify source of leak. Oil is changed once per year, drive car very little. Nothing on floor in garage or seen on motor.
Car is 2006 with 32000 miles. No other issues, maybe its time to sell