I've always liked the meguiars cleaning polish, it's a pretty simple product just rub it on with a cotton rag and buff it off with an old towel. If you want to get a real shine go over it again with a wool buffing pad. Also use it on the chrome on my semi, seems to seal it up so it only needs a quick rub to knock the dirt off every now and then
Look up wizards polish
Most of thier products are similar quality to 3m, some actually better. Far better than the junk they sell at your average auto parts store.
They have somewhere a list of steps to go through.
If you show pics I could get you headed in the right direction
Seems that you are looking to do what I dealt with. Had a pink tractor bought used so wanted to see if I could fix it. I did a small test on the Case hood by hand with some Meguires fine cut polish I had and saw that that would fix the paint so I ordered a dual action polisher, pads and an assortment of liquids. There was a place in Ontario that I ordered everything from so that was a factor in how I choose products. There is lots of info on the web.
Pics of test run by hand, a JD hood done with the polisher and a medium cut polish, and the Case after a full job. On the tractor you can see how orange the paint is on the steps where you can't polish. The steel was all like that but with some time and effort the oxidized paint is removed so red shows again. Medium cut polish, fine cut polish then a sealer. I used the orange pads from Lake Country for the bad stuff but white or black will work for most needs, like if you had a car with good paint you are giving a polish.
Last year I went and got some good clear coat paint. Sprayed it onto an old combine and it looked like new after. People thought I repainted it. Only prep I did was pressure wash it. If it was worth more it really should have been sanded but hey it passed the 20/20 vision test. 20 eyes at 20 feet away
Myself and a neighbor have each done a couple 4wd's with Dakota shine. Works very well. Big thing is apply thin coat, does not need to be thick like clear coat. Makes all rubber and plastic surfaces really pop. For the $100 and a day of elbow grease it adds alot to a tractor for resale.
I have used Meguires medium and also fine cut polish on lots of oxidized equipment with pretty amazing results. It does not seem to work as well on plastic or epoxy finishes because the fading is deeper into the layer than if it is an enamel and the oxidation polishes off the surface. Cut polish still helps some though and then a few layers of good wax to finish it off and seal everything really makes the old paint pop. The shine is always impressive even if you can't restore all the fading. You can buy Meguires in gallon containers for some of this bigger equipment.