Fuel Injection Pump Problems on Yanmar Marine Engine 315HP 6LPA STP

I have had two Yanmar engines destroy themselves when the fuel injection pump has seized allowing free flow of fuel.  The pistons have hit the valves causing a catastrophic failure. This happened after 146 hours and after 315 hours so the engines were hardly run in. In both cases an independent injection pump engineer has confirmed that it has been due to insufficient lubrication within the pump. The diesel fuel provides the lubrication. The fuel has been analysed and the viscosity has been normal. This suggests that the design of the pump is not reliable for current diesel fuel specifications. Has anyone had a similar experience with a Yanmar or other make of marine engine? Does anyone have any ideas on possibly using a fuel additive to improve the viscosity within the pump.