blue smoke ?

[brad306]

hi all, just a quick question really as ive been told this could be numerous things, when i start the car, it chugs to life and sounds rough as nails till it gets warm, when it reaches around 70degrees, it starts chugging again but puffing blue smoke out, could this be the valve stem oil seals or something ? it will do this for about 2/3 minutes till it clears itself and im just starting to wander what it could be, im running it on veg and diesel if this has anything to do with it, thanks...