Excessive oil consumption in Luv Dmax 3.5L year 2006 and posterior

The truck has 260,000km, the engine was made 8 months ago, but it continues to consume a lot of oil, it has no boats, the PCV valve is changed 1 month ago and stop throwing white smoke but continues to consume oil. It has a power, stable and toned motor. What can be? I have heard that this truck always consumes but 1 liter every 600 km is exaggerated.

Oil consumption is usually because the machine is thrown out or is burned by the engine,
it enters too much oil to the admission, through a defective PCV valve or a bad breathing design of the crankcase, this has already happened to me.
When it is burned by the machine, it may be due to valve stamps in poor condition, whether crystallized or broken
valve guides spent or with too much game ..
too much wear of the cylinder, poorly rectified cylinders, rings in poor condition, poorly applied.
file: /// c:/users/compaq/downloads/[isuzu] _manual_de_taller_motor_6ve1.pdf