Engine Chatter When Warm Up

[arena314]

Hi, so everytime I start my car cold it makes a chatter noise coming from what sounds like the valves. It's everytime the car needs time to warm up I usually give it about 5 minutes of idle time every morning to warm up. Why is it that it chatters when its cold but after 5 minutes or more of warming up the noise completely goes away? Could it be the oil that's in the car? Lmk what you guys think. Thanks in advance