Hi Ace D4D white smoke some days yet not others :/

[Throttle]

Hi

We have a old 2003 Toyota Hi Ace with D4D engine and almost 200k on it now, over the last few months its started to blow white smoke out when its starting up in the morning but its not every day it occurs one morning its fine then another its back 

It always runs fine and levels seem fine so bit random how it happens one morning and then next its back, this isn't just since sudden cold weather has shown up....... Any ideas as to what could be the cause of it ?