I have a Johnson V140 1987 less than 60 Hours, new lower unit. Has been sitting for 7 years in garage. Some old gas still in tank along with new ( 2 gal.old). 6 gal new. Test run left oil slick on prop and driveway, plus fogged the neighborhood. Should I just empty the tank and start fresh, or any other causes you can think of? Also broken clamp on VRO hose.