ok, well the reason i suggested a compression test is to see just what kind of compression you have. The engine may start up and run but you could have a ring problem causing the blue smoke. There may be a slight loss of compression because of that.
But even if the compression is good, the blue smoke is a sign of oil comsumption , oil bypassing the oil ring on the pistons. It also could be oil being sucked in through a pcv valve or even getting sucked in through the oil seal in the turbo if this is a turbo diesel.
Have you had to add engine oil to it more regularly than normal since this started happening?