Technical noise

[bravo jtdM150]

done a oil and filter change wr 5-40 oil to see if it would cure a tapping noise on cold starts, but its the same.
i start engine, first few seconds it chatters then no noise then about 30 secs later theirs a distinct ticking noise, the noise doesnt get louder or quicker if i rev. the ticking lasts around 2 minutes then goes. if i rev to say 2000rpm when its cold theres no noise, only when it rests at idle this tapping/tick arrives - only for a few minutes. ive tested another multijet 150 and its doesnt make any weird noise on cold starts. mines gt 10k on clock and is only 7mths old.
do the injectors make a noise like a tapping? if its a tappet it would do it when i rev as well, only on idle when cold. is there anything to quieten this noise like treatments?
are the petrol stations using winter diesel or normal diesel?

 

[Big Black Stilo]

see here

 

[Juliet Bravo]

You could have partially blocked oil passage that isnt getting the oil to the tappets straight away, unlikely on a car your age - next time the oil is done ask to get an oil flush done or buy some yourself and put it in before taking it to the garage for the change.

Strange that the ticking doesnt increase when you rev, have you checked around the engine bay for loose things sounds as if something is knocking on the engine