Smoke coming out of tail pipe Options

[Jules88]

So I posted on here several months ago and received some pretty good advice, but now I'm having different problems.
I have a '94 Celica ST automatic, with a rebuilt '94 Corolla 1.6 engine in it. Well some parts are from the Corolla, some are from the Celica. We finally put it all together and now it runs, but I'm having the SAME problem I had with the old engine - grayish smoke coming out of the tail pipe. I know oil is burning and I probably should have changed the rings and pistons, but could it be caused from anything else? Or is it a coincidence that both engines are giving me the same problem? The old engine broke down on the freeway - a piston shot through it creating 2 large holes. So I got a different engine from Pick A Part. I know it probably won't pass smog at this point, but I'm just wondering if anyone has any advice on what I can do to minimize the amount of smoke coming out, etc. Someone mentioned checking the spark plugs for oil then gapping them, and doing a transmission flush, and using synthetic oil or some kind of additive, Marvel Mystery Oil, etc. Give me your thoughts on this, I will try everything possible before spending money on rings and pistons. I appreciate all comments. Thanks![size="3"][/size]