Yes the oil is shared, when you change the oil. One nice "safety feature" that comes with this type of injection system, if you have a catrostrophic event where you loose engine oil (loose a drain plug, knock a hole in the pan, blow a line, plow a filter, etc) the engine will quit running before it looses all its oil because the injectors will not longer fire...
This type of injector is extremely ******* oil. The way the injector itself works, (all are similar but I am more familiar with the 6.0 so that is what I will describe here) The ongine oil is pressureized in the HPOP (High Pressure Oil Pump). The minimum oil pressure to fire the injector on startup is ~400PSI (this oil pressure is created by the HPOP being turned by the starter in turning over the engine to start it). This high pressure oil is transported from the HPOP through the heads via cast-in oil gallerys to the Unit Injector, for each cylinder, in the case of the 6.0 4 per head. This oil flows into the "top" of the injector. There is a shuttle valve located in the top of the injector. This controls the oil flow into the injector and to the intensifier piston, the intensifier piston is a 3x "amplification" of the oil pressure, this is the pressure the fuel is injected. The fuel fill a "chamber" at the bottom of the injector, below the intinsifier piston, this fuel it pumped into the chamber at lift pump pressure. Injection pressure is created by the oil pressure on the intensifier piston. The shuttle valve, moves back an forth to fill and fire the injector. This shuttle valve is one of the places the oil is sheared, or quite literally "cut" by the motion of the valve shuttle, as it moves very quickly through the oil stream. This oil stream is under a great deal of pressure. As stated earlier, from 400psi at start-up, to almost 4000psi at a WOT loaded acceleration. The pressure the fuel is injected into the cylinder can reach up to ~20,000psi at injection......
This is one reason the OCI is "short" wither using dino or synthetic is because of this shearing. I have read that some owners that have done lab testing on the oil, that oil that started life as a 15w40 oil, at the 5000 mile mark had been sheared to an equivelent of 10w30. Also, that shuttle valve suffers from a phenemon called "stiction" where when the oil is cold, it will stick on the bore, causing low power, and a miss after cold start-up. I have this right now, and need an oil change, once I change the oil it will clear up. The system is not perfect, and stiction was not an issue in the 7.3PSD injectors because there was a return spring in the bore for the shuttle valve, this was eliminated in the 6.0.
DELO is the original Diesel Engine Lubricating Oil designed for Caterpiller engines during the 1930's to prevent piston ring pack sticking , combat high PH and lower piston skirt wear. Its been around a long time
