Nissan Repair: 1994 Sentra is smoking after running at highway speed, nissan sentra, piston ring

Question
I have a 1994 Nissan Sentra with 1.6 liter. I have recently replaced the all of the timing components, had the head professionally refurbished, honed the cylinders, and added new pistons and rings. Now it runs PERFECT. The problem I am having is that after running at highway speeds for 15 minutes or so, it starts blowing oil smoke.. as if there is pressure building up and forcing oil in the pistons. I have replaced the PCV and also the EGR valve (engine light was on before any repairs indicating EGR). I let the car sit for a day and pulled the sparkplugs. I had oil on top of 3 out of 4 cylinders. I thought maybe the valve job was bad, but it doesn't make sense that it would be on 3 cylinders... and if that's the case it would have cleared up instead of getting worse while driving... right? Any ideas would be GREATLY appreciated... I am losing my mind and wallet on this old car.

Answer
let me answer this to the best of my ability.  my first thought was that, i know what its like to try to test everything w/o doing any major work, but i think your problem lies within the rings that you replaced. they may have not been seated properly.  this is just an assumption.  did you have this problem before you did the piston/ring job?  i think you are right about the pressure in the pistons/forcing oil...etc.  black smoke usually indicates worn rings, but i think they are improperly seated, and if you had this taken to garage to be done, theres a chance they didnt change them at all.  garages are sketchy, thats why i diy.  another answer to your quesion about the clearing up, it wouldnt clear up if its a steady leak of of oil.  check you oil level and see if its slowly going down, and also try using a motor flush, and change the oil and use lucas in replace on one quart.  lucas is supposed to seal warn rings, gaskets, etc.  for money reasons, i would go with my last suggestion. it does become a headache and a pain in the wallet.  the cheapest route would be engine flush (3 or 4 dollar can).  run that with your current oil and let idle for 5 minutes. drain oil completely.  add 3 quarts of high quaility oil and 1 quart of lucas and a new oil filter. this may fix the seals/rings or your problem all together. *may*.  it will only cost you about 20-22 dollars this route.  if this doesnt clear up, you may need to take the head off to examine what went wrong in the installation.   good luck man, and let me know what you find out...
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