They are high pressure oil fired injectors, but that has nothing to do with high crank case pressure. Think of it as 2 separate systems the low pressure system lubes the engine and feed the high pressure oil pump, the high pressure oil from the pump fires the injectors, I believe it's 500psi just to make it idle. They mainly leak oil from abuse, high engine hours, miles, age, and lack of maintenance. Squisher summed in up nicely, except I wouldn't bother with the synthetic oil, just use the correct weight and grade and keep it at regular maintenance intervals. Good Luck!