Mercury - Oil Change Kit, 75/90/115HP FourStroke, 1.7 Liters Maintenance 8M0081913. Overview. These 1.7L Mercury FourStroke engines-75, 90, and 115HP-are pretty tough, but they run noticeably better when the oil is fresh. They see a lot of mixed use: long idle zones, hard throttle bursts, hot days sitting on the water… all of it adds up. When the oil starts getting tired, the motor will feel a little lazier, maybe idle a bit rough, or just sound "warmer" than it should. This kit makes the oil ch