93 Honda Civic sedan 1.5l
Bought the car used and it was blowing lot's of blue smoke and drank oil a litre a day. I rebuilt the engine myself, put new rings on and honed the cylinders, I had the head done at a machine shop. Put it all back together ran fine no smoke passed emission test very well. After about 8k it started blowing blue smoke again real heavy. I assumed the reason that this happened was because I used synthetic oil and overfilled the crankcase, or perhaps the PCV valve faulted. I did a compression check and it was all over the place.
So I bought new rings again, honed the cylinders, cleaned the heads really well and checked them, changed the valve seals again, put it back together. Used regular oil and did not overfill Ran fine no smoke till around another 5 to 8k and again huge amount of blue smoke

What possibly am I doing wrong??

 

Stupid question, did you use a new headgasket? What about check the block for warping? How are you driving it while breaking it in after the rebuild? Are you using a cheap ring compressor for the rings orgapping the rings incorrectly?