RFB

I have a 91 Legacy wagon that smokes like crazy. I bought this car a few months ago and while test driving it it ran fine, no smoke at all in the 20 min I drove it. On the way home, 30 min later it started smoking a little, and got worse the rest of the way home. Now when I start it, just idleing in the driveway it can smoke out the neighbourhood. I have checked the pcv, it's fine, no oil anywhere in the lines. I pulled the plugs and the left front cylinder is the one burning oil, it's the only plug that came out black. First thing I tried was changing the valve seals, didn't help. I checked the compression, got 200 on 3 cyl, 191 on the left front. Could it be rings? This car has 170k on it, but from what I have read, it should go alot farther. It runs fine except for the smoke. Any suggestions on what to check? Thanks.