grinding sound when car starts / cold

[gymkata]

It's gotten a lot colder here in the midwest. My car has been fairly quiet up to this point.
Since the temps have hit around 10-15 around here, the car starts making this sort of rotational rattling sound when the car IDLES. It's not that loud but it's fairly annoying. It goes away as the car warms up. Any guesses what could cause this.

I thought that the fan was hitting the plastic covering.
Let me know if anyone else has had similar problems.
Thanks in advance.

[markus]

could be ticiking valves and goes away when engine warms up

[632 Regal]

use a thinner synthetic oul such as mobil 1 0w-40 or 5w-30.

[western99]

I still have not figured it out.

It's gotten a lot colder here in the midwest. My car has been fairly quiet up to this point.
Since the temps have hit around 10-15 around here, the car starts making this sort of rotational rattling sound when the car IDLES. It's not that loud but it's fairly annoying. It goes away as the car warms up. Any guesses what could cause this.

I thought that the fan was hitting the plastic covering.
Let me know if anyone else has had similar problems.
Thanks in advance.