These engines will require 5W30 oil otherwise the valve guides start to wear quite badly. Yours has probably done this, and nothing but a new head or engine can solve it.

What colour is the smoke out the exhaust?

Thanks for the replies, The smoke just looks light grey through the rear view mirror, i thought it probably would be valve stem seals but i remember my old 1600 cortina suffering with stem seals and that used to kick a cloud of smoke out on start up which my fiesta isn't doing apart from the once mentioned before, which is why i wondered if it could be something else with it pinking and holding back when accelerating hard , can the stem seals be done with the head still on. i made a tool years ago and did the seals on my cortina with the head on, if not am i looking at a head skim as well. just trying to weigh up whether its worth getting into engine strip on an old car where one thing will probably lead to another