Yes, unfortunately clay bar and wax may not be enough for your oxidized paint.
You need to...
1.wash and degrease your car.
2.clay bar
3.rubbing compound
4.polish
5.wax
Remember if you don't know how to do any of what I listed. Then don't try! Rubbing compounds and polishes can be very abrasive and destroy your paint if you don't know what you're doing.. If it comes down to it, always use a "reputable" professional detailer.
If you have black trim around the windows, which may be oxidized you can use Peanut Butter to get rid of that.
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