Hey,
I am looking for a solution to my vq35de oil consumption, my cylinder no. 5 is always oil fouling plugs after a couple of hundred miles. I decided to Teardown the engine and replace rings, I am not looking for some fancy rebuild, just a full engine rering process to solve my blowby and I am for sure going to smash this precat and never let any catalyst in the exhaust pipes near the engine. I dont mind the third catalyst though. My question here, has anybody Tore this engine apart after a catalyst contamination? Is it only going to be a rering Job or should I prepare for worse? I measured compression and I am getting a solid 170 psi across 6 cylinder s. The Problem is I live in Germany and this large displacement engine isn't very common here, people usually buy 1,6 Petroleum or 2,0 Diesel engines so I am always lost when it comes to this engine.

If you are oil fouling #5 but compression is even across the cylinders the problem is in the cylinder head not the ring or cylinder wall. Most likely just a valve stem seal.