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Hello and thanks for trusting me to help you today. I am a licensed diagnostic and repair technician, I look forward to working with you.Can you explain what type of noise you are getting on cold start? Is it a tapping or rattle type noise?
I would say it is more of a tapping sound and it only happens once or twice a week and the noise comes as the engine fires
I suspect this is the hydraulic tappets, These use oil to pump up and take up the clearance between the camshaft and valves. When the engine is initially started cold the oil is thick and has all settled at the bottom of the engine, when the engine is started the cold thick oil will take a few seconds to be pumped up to pressurize the tappets and stop the tapping noise. The same applies to the timing chain tensioner... for a few seconds the tensioner will not apply full pressure onto the chain allowing the chain to rattle which often sounds like a tapping/light hammering noise which quickly disappears.This is not a problem, or a fault of the engine and is acceptable providing the noise clears within a few seconds but there are several factors that effect it. Old oil will be thicker than new oil so if your car may require an oil change soon (check your service schedule) That mixed with the recent cooler weather will cause this.
If the car has just been serviced with an oil and filter change and the noise is now more prominent the wrong oil may have been used which is slightly thicker than required for our climate.