I've got a B-23 ('84-only turbo) with 190K and it consumes about 1 quart of oil in 600 miles of highway driving. The turbo is rebuilt, there are no external oil leaks, and the engine could do better on the jiggle test. There is a visible fog that eminates from the turbo end of the blowby tube, but only when I rev the warmed-up engine--not a real blast, but it can be seen for an inch at the end of the tube. The way I see it, it's either rings or valve stem oil seals, or both. The engine has plenty of power, is always allowed to warm up before driving, and has been on a diet of synthetic oil since 60K. The turbo gauge, at idle, is nice and steady. Approx 100K of the mileage was put on in the last 2.5 years, and the oil consumption began to climb a year ago or so. Has anyone cured high oil consumption by replacing the valve stem oil seals? I haven't done a compression test, but I can. Any help would be appreciated.

Thanks--Steve Oakes