Weird smoking problem, need some help!

Here's my problem. My car was running fine, then I blew the turbo about 3 weeks ago. I replaced it with another used t-25 from a friend's car. It had some shaft play, but nothing outlandish and it didn't smoke when it was on his car. Now my car smokes like you would not believe......but only after 5-10 minutes of driving and @ idle. I start my car up and everything is cool, no smoke, oil pressure is exactly between the high and low lines, we're good. I can drive, stop, and go as much as I want in the first 5 minutes, but I am screwed after that. The first time that I stop after I have been driving it for about 5-10 minutes...SMOKE! Enough smoke coming out of my tailpipe that it almost obscures my view of the road. My oil pressure drops until the needle is barely above the low line (not the very bottom "empty" line) and stays there. As long as I am on the gas I am good to go, but between shifts there is a little bit of smoke and @ idle there is an assload of it. The smoke looks white, but I've only driven it @ night, so I would imagine that there is a blue tint to it because I know it smells like burning oil. There is also some smoke coming from my engine, but not a whole lot. I haven't done a compression test, but I plan on doing one this weekend. Other than "Do a compression test" are there any ideas out there? Maybe we're just dumb, but my friends and I are stumped. Thanks