06 terios 1.5 engine rattle knocking


hi i have a 06 terios sx 1.5 with 40000 miles
after a 2 hour drive on the motorway i started the car the next day and there was a rattling sound from the engine at 1700-2000 rpm you cant here it when the car is cold but once its warm you can here it the car drives fine no loss of power no missfires it also does it when the car is not in gear
sounds like its coming from the bottom of the engine and not the top

if it was a bearing/rod which oil should i use? as its dew a oil change and are there any other things i could try to stop the noise
could it be a cam belt tensioner Unknw
it only does it at the stated rpm below or above that rpm theres no noises
car has just ran out of warrenty so any help would be deeply apprecatied thanks