Oil Sample

[Rawze]

whats the hp, torque, and rear ratios of the truck> - more infor may help.

What kind of oil(s)?, etc.

Any addatives?

btw. viscosity is also falling off. Have you tried using a gallon of gear lube at every oil change like recommended on here?

Have you done EGR tune-up? etc.?

What is your fuel milage to the pump typically?

what kinds of operations? mostly city? highway? flat? mountainous? -- Light or heavy? etc.

Also, its kinda normal for cummins engine to use a gallon of oil as the oil starts to wear out. Its well known, especially as the engine gets older.

Maybe provide a screen shot of your regen history? - That would tell a lot too.

Maybe some photos of the face of DOC and DPF when they start to act up? - That could reveal a lot too.

Have you pressurized the whole engine (not just the CAC) and checked it for boost and other leaks?. Checked the Doser, cleaned its nozzle?, checked it for leakages?.
Have you checked the valve guides for leakage? - this is common problem as well that cause what you describe. Maybe disconnect exhaust off back of turbo and hold sheet of white paper behind turbo and have someone crank engine to see what spatters onto paper when it cranks up after it sits a while. Maybe pull exhaust manifold and see if valve stems are wet woth oil.

When is the last time the overhead valves were adjusted and overhead cams inspected?

-- I.E.> Its an engine and things wear out. At some point, you have to take things apart extensively to find out how badly. Running around with an engine in an unknown state and health = problems that are difficult to solve and plague someone. a truck owner should ALWAYS KNOW to some medium extent what condition their engine is in,.. otherwise they will be at the mercy of fate, and that is no way to run a trucking business reliably. Being pro-active and tearing into things yourself regularly is that prevention.