2005 mercury xr6 150hp s/n 1B042693. I was fishing a bass tournament this weekend and after running across the lake my partner said theres an oil slick on the water behind the boat … once we got back to the ramp I pulled the cowling and the entire engine was covered in oil. Appears it was coming from reservoir cap on the engine. Tested the float and it works but that’s as far as I’ve got. Wondering if it’s the cap seal. The cap was on tight. Any words of wisdom would help allot.