A few months ago I got a real good deal on a 2002 Toyota Sienna van trade-in in Minneapolis with 155k on it. I drove it 1700 miles home to Seattle, and along the way I needed to put in 12, yes 12, quarts of 5W-30 oil. (average: 1 qt./140 miles) But there was no smoke coming from the tailpipe at all, even at first start-up in the morning. I also had it put up on a hoist, and no oil was leaking out.
When I got home I had the valve cover removed at a Toyota dealership to check for the infamous oil/sludge problem. There was none, but all the spark plugs were oil fouled but still functioning. When the dealership checked their national maintenance system, they discovered this van was extremely well maintained with all of the oil changes done at a dealership and on time. And all the 30/60/90k checks were also done on time.
They were at a loss to explain where all of the oil was going, and especially surprised there was no blue smoke coming from the tailpipe. And the check engine light never came on the entire trip.
So I took it to a repair shop I've used before, and the manager was also at a loss to explain it. But a mechanic overheard us talking and came over. He reached in behind the engine, pulled out the PCV valve and said, "This is an after-market PCV valve, and it's clicking when I shake it, but it doesn't sound just right." It turns out he was a Toyota master mechanic. I wasn't even charged for his advice.
I purchased a new Toyota PCV valve for $10, put it in and went and had the van emission tested. It passed with no problem. I brought the oil level up to full and drove it for a few hundred miles. It used no oil at all.
In the first 1000 miles after putting in the new PCV valve, it has used only 1/4 of a quart of oil.
But here is my question. The previous owner had to replace the catalytic converter 5000 miles ago, because the check engine light kept coming on and the code indicated that was the problem. In your opinion, do you think that all of this oil that has gone through the engine will cause a premature replacement of this fairly new catalytic converter?