Mercury - Quicksilver 5W-30 Full Synthetic Blend TDI Diesel Engine Oil, 4 Liters Marine Engine Oil Synthetic Blend 8M0069602. Overview. There's something deeply reassuring about knowing your diesel engine is protected by oil that's built for the kind of punishment boating dishes out. When you start your TDI and feel that smooth, low rumble settle in, you know whether your oil is doing its job. Quicksilver 5W-30 Full Synthetic Blend TDI Diesel Engine Oil, part number 8M0069602, is the kind of oil