Anyone have any experience on this?

In the very cold weather, there is a really loud metal sounding 'slapping' noise - it seems like it is coming from under the valve cover, right behind the secondary air check-valve. The clicking noise increases with engine speed. After the car warms up, the noise goes away.
In the summer, there is no noise unless l turn the A/C on. And it stays noisy until l turn the A/C off.

Relax, it is probably your valvetrain making the noise. You might want to consider using a different grade of oil. 0W-30/40 perhaps?

My 95 ti does the same thing. it is just age.