Livin the Dream

Hi newbie here- 88 C4 . Been reading about the fog light upgrade to 50W bulbs . One post said that on some the fog lights were grounded through the high beams and they would glow. Not sure what size bulbs are in my fogs , the fuze is still 10 , however my headlights glow when I turn the fogs on. The green wire is the one I am going to splice and run to a seperate ground?(other is purple) Also do I have to splice it at both lights or just on the drivers side? Oh and one more question on oil.
Not sure what has been run in the car - it has 86K. Any special flush or procedure to put in synthetic? Will a change over benefit or would it cause any damage?
Thanks Kevin