D2 Cylinder imbalance

here's one for the td5 gurus
my truck started smoking a couple of weeks ago and it appears blue which would point me to engine oil getting burnt
turbo appears fine and oil level isn't dropping
its not excessive but annoying as i hate cars that smoke and normally mine doesn't

so i got to looking at injectors but i would expect black smoke from them if over fuleing or white if under

however ive plug a Snap On diagnostics in and appear to have a different reading on cylinders 3+5
im going to collect my Nanocom tomorrow and see what that says
however my query is what should i get in the way of readings and what does it mean ?
thanks in advance