Archoil AR6400D max creating smoke?

[DAF XF]

Hi put the above additive in the tank last Saturday (08 2.0 auris 153k) as directed after following the brilliant egr cleanout advice on here. I had cleaned it out a couple of weeks prior and all seemed fine. No big pick up in mpg or performance still a bit reluctant to start when cool but maybe slightly more pull low down the reva when warm. 

Anyway to give the rest of the engine a help I used the ar6400 and just as last few days as i dropped to below half way down the fuel tank it has started producing lots of blueish smoke when starting and a bit lumpy I think is how it's described. RPM feels like it's jerking up and down and pulsing a bit for a minute or two then clears and seems to behave as normal. It may be coincidence but the steady 48mpg also around this point started dropping to 46 and was very hard to increase despite trying.

Is this normal given I've never seen the car produce anywhere near this volume of smoke? Is that it clearing  rubbish out or has it done something and now means the cars burning oil?

i filled up with more fuel last night and still encountering the same today  

ive dipped the oil and not noticed any difference yet anyway.