Horrible sound whilst idling

[NDGTI]

Hi all
Only started in last couple of days
Car sounds fine when driving, but when I come up to traffic lights out traffic, the noise from engine has changed from normal sounds to rough as a badgers arse
Any ideas ?

[colesey]

A clattery noise from the right hand side of engine at idle whilst the engine is cold? Does it go away with a tiny bit of throttle? That could be the cam chain tensioner not pressurising properly whilst the oil is thick in this freezing weather. I had this recently and my oil level was towards the low end of dipstick - topping it up to max made the noise go away.