Here is a snapshot of the diagnostic progression I experienced and the results after I noticed I was consuming oil and blowing large amounts of smoke out the tail pipes at certain times when driving.
Lots of smoke out the tailpipes when accelerating immediately following a stop at a light. Idle for roughly two minutes at the light after driving and then step on the gas when light turns green and puff, a good size plume of smoke. So it led me to believe it was a change in vacuum that was causing this. Positive pressure builds up then negative…then when it switched back to positive the smoke show would appear. Built up oil vapor with nowhere to go? I thought clogged PCV. (No smoke under WOT, no massive amounts of smoke during cold starts just a little blue puff for a second or two.)
1.) Went to the dealer. They swapped in a new PCV and cleaned the two PCV lines that lead to the vc’s. Problem was solved for 30 miles. Then it returned.
2.) Went back to the dealer. Performed compression test, removed I/M (it was full of oil) and replaced the PCV yet again. This time they also replaced the two PCV lines that lead to the vc’s. Problem was solved for 75 miles this time. Then it returned. I did my own compression test and the numbers were well within spec.
3.) Went back to the dealer. They literally repeated step 2 and gave me the car back. Only difference, I found a little check valve located under the I/M in a diagram during my research and iirc it actually routes bypass/oil vapor like residue directly into the I/M. It is not part of the PCV. The dealer yanked the I/M and replaced this part. Problem solved for 100 miles. Then it returned.
4.) Went back to the dealer. They did a leak down test and determined my valve seals were shot. Ordered new heads. Cleaned PCV, PCV lines and I/M. Installed new heads. Problem solved for ~300+ miles. Problem returned.
5.) Went back to dealer. They brought in a “specialist” and tore down the motor (removed heads etc) and performed additional “diagnostic procedures.” They discovered that every rod bearing was scored and that I had multiple egged pistons allowing massive amounts of oil to pass into the combustion chamber. Ordered the following parts: Short block, intake manifold, passenger side valve cover (new design) because you cannot get a vc gasket on that side without purchasing the cover (WTF), PCV, PCV lines, cam covers, multiple vacuum hoses, multiple coolant hoses and a slew of other odds and ends. Basically I ended up with a new engine top to bottom but it was piecemeal instead of a long block in one shot.
To give you an idea of how much oil I was going through…it was 1QT every 375 miles, no joke. I monitored this like crazy. The dealer also did their own oil consumption testing that matched up with my findings.
I may be leaving out some details since I’m doing this from memory and my notes are on another laptop. I did document most of this on this site in a thread so we can reference over there to compare to. I can also pull the invoices with the tech notes but they are horrible. Big block of text without any punctuation.
Hope this helps.