Yellowing on white trunk lid

[Mless5]

I have a little problem happening here. I have '87 white car that I love to death. I used Zaino chemicals last time I detailed it. The problem is that vertical portion of the trunk lid becomes cloudy and yellowish after a while. I have a feeling it will clean up, but the question is why does it happen and how to prevent it?

Thanks!

P.S. I tried taking pictures, but none of them show the real issue.

[Detaillab]

Re: Yellowing on white trunk lid

When was the last time you detailed it, and when did you first notice the problem? Do you have a single stage or clear coat? You most likely have a single stage with a car that old, and white. Again I think we need more information, but I would try claying, and then Meguiars Deep Crystal System paint cleaner, followed by your favorite wax. It is very likely that your paint is just dirty.