how to repair scratched and dull paint

Paint problem after a misstake with a 1984 Opel Kadett
I was washing away oil and pine-tar from the outside of my car after having the underside treated against rust as usual. The tar had gotten a litle bit too much time to cure so it was difficult to remove. Because of a missunderstanding I did use a household soap on some parts of it without knowing that there is some grinding agent in the soap. When the car had dryed I saw that almost half the sheetmetal was completely dull with small surface scratches that do not go through to the primer. The paint is mostly original paint which has gotten quite thin from years of use. In some places it is repainted with Motip acrylic paint. The car is old and cheap so I do not care about the perfect gloss but I want it to be better than it is now because the car is otherwise in very good condition. I live in Finland where the climate makes cars rust very qickly.
What shall I do? Please give advice.

Try having it buffed out. Only problem with this is you generally will need to have the entire car buffed otherwise the gloss/shine to paint will not be uniform. If they are too deep to be buffed out(doesn't sound like they are) you'll prolly need to have the scratched area re-cleared. If this is the case I would recommend doing a complete paint detailing job on the area's not re-cleared(i.e. clay, polish, etc...). Or another option is detailing the entire car yourself (either by hand of with a buffer/polisher) time consuming but prolly the cheapest way if you don't want it to be absolutley perfect. Check out this thread for further info on detailing http://www.automotiveforums.com/vbulletin/showthread.php?t=389946 . Good Luck. Peace-

Use a rubbing compound that is LESS abrasive than the soap that was used.

Then move up to a finishing compound that is finer yet.

A good hand waxing should finish the job.
(And you'll get a pretty decent workout from it)