Sorry for bringing up this ancient thread, but I was wondering if you could tell me if you solved this problem. You probably don't even have the car anymore... but I thought I'd ask anyway.
I still have the car and it quit using oil after I installed smaller lines. This engine has about 170psi compression so I was thinking it just has more blowby creating more of an oil mist or something. Anyway I went with lines about half the size of stock and the oil use stopped. I still drive the car a couple of times a week.
Wow, thanks for the reply! That's great you still have the car. Mine is also a low k car; about 80,000 orginal km, but I'm consuming a ton of oil. I suspected the piston blow-by problems you were trying to diagnose. The car has obviously sat alot throughout it's life.
Like yours, all the compression tests came back within 1-2 psi of each other. It is leaking a bit at the rear main, but not enough to justify this amount of consumption. My wife was following closely in her car and observed it was blowing a bit of smoke when I had it at wide open throttle, but only a slight amount. She also couldn't be sure if it was blue, black or white smoke (she couldn't keep up in her Echo).
I did have a question though, by replacing your lines, do you mean you replaced your pcv lines? Like the line going from oil cap to throttle body & also the line going from pcv to upper intake?
Mine was smoking too. I only replaced the PCV to upper intake line. I just have one line running from the PCV to upper intake. The oil cap line still connects to the throttle body.
Hmm, I find it interesting that you were able to fix this with a smaller diameter line.
In the thread below, it says that the problem can be fixed by using a "Larger" ID PCV line, or by installing a second pcv valve in the drivers side valve cover. It says the solution is to have a larger volume of crankcase gases at a lower velocity.
Well, try one and see what happens with your application. I tried two large lines to the same PCV, that didn't work. (The PCV had two outputs. I tried a large line to the PCV directly....meaning I removed the 90 degree piece. I went the larger route first. I didn't try the extra PCV setup, but I thought about it. I finally decided to try a line with a shutoff valve do I could regulate the pressure. That didn't work all that well because you had to have the valve almost shut to get a pressure drop. Then I decided to go with a smaller line. The first small line was too small and wasn't "holding on to" a piece of paper placed over the oil filler with the engine running. (Air tube to the TB blocked of course).
I even installed a water trap in line. Just a small one you get from Lowes or Home Depot. That actually worked. But I got tired of draining it. This is a setup I have seen on many cars and trucks, especially supercharged ones where there might be more blowby.
I would try the easiest one first. I installed a clear fuel filter so I could see what was going through the lines so I didn't have to wait and check oil consumption.