Just a guess ........
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There *appears* to be an issue with the 3.5 V6 ........
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not sure if this issue is limited to the early 3.5's .......
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faulty oil control ring(s) .......... ring material ? ........... tolerances (tight or loose (fit) ...... or the placement (on the piston - too high or low) ? ........
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or high crankcase pressure ......... if that is the correct term .....
?
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PCV valve ? ......... I don't believe the PCV valve is the problem, but rather a symptom of another issue ....... regardless, PCV replacement on the 3.5 is common .......
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one of the above ....... or a combination of the above ......... can/may affect the operation of the PCV valve, etc ...........
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again, a combination of the above appears to lead to oil consumption - signficant oil consumption at times ...........
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again, a guess - I am semi familiar with the operation of the internal combustion engine, but certainly not a mechanical engineer .....