thallium

I'm the new owner of a 2013 GS350. I washed the car this weekend and just noticed a lot of smudges on the roof that did not wash off and are slightly rough to the touch. I did not notice them when I bought the car but they might have been there. Naturally they're in the hardest part of the car to see and fix.

I'm not sure what it is, possibly tree pitch. What would be the recommended procedures to start with going from light/safe to more severe? Are there solvents that won't damage the clear coat light denatured alcohol? Will a clay bar do anything? Cutting cream? Along with this, the paint is a little uneven in glossiness and probably could use a good polish so maybe I need to get a DA buffer and do some work but not sure where to start.

14RX350

A lot of people just send their car through the carwash and never really give it a good hand scrub. I noticed that when I purchased my car... It had a lot of little things that looked like they had been baked on there for a while. Took some good scrubbing during the next two washes to really get it clean. So thats my first recommendation... just doing a wash again and giving those spots a good scrub. That will set you up for the next step if that doesn't work, which would be claying. Next would be a light polish... Nothing too agressive. You can just apply by hand. Remember to put some protectant on afterward.

Merlinii

Depending on what it is there are a few processes. You may wish to try some All Purpose Cleaner (APC) - Simple Green may get the "smudges on the roof".
I have used Isopropyl Alcohol (IPA) many times on auto paint with no issues. However, a Last Step Product (LSP) wax, sealant etc.will need to be applied after.

The "paint is a little uneven in glossiness" could be anything from oxidation to the beginnings of clear coat failure. These areas should be approached with caution.
I would try some less aggressive methods before using a DA (Mild chemical, Clay bar etc.) before a "good polish...DA buffer". In the end, that may be the route.


Merlin

thallium

IPA seems to be ok as I've seen many recommendations on it but does it need diluting? I was thinking denatured alcohol, but maybe that's too strong? I might try simple green, then IPA, then clay bar if the previous step/steps weren't effective.

I don't think the clear coat is failing. My guess is that the previous owners just did not care for the paint that well and probably used auto car washes or just never did a polish. Parts, like the doors seemed to have a good mirror finish, while the roof was just not as sharp as it would be the hardest part to polish generally and there are a lot of micro scratches and swirling.

JimInTN

Try some Mcguires liquid or paste car wax in a maroon bottle or tin. I use it and it will remove/dissolves dried bug residue, tar splatter, etc without damage to the finish. Just apply it, let it sit for a minute or two, rub some more, and you should see some progress. Adjust accordingly. You could also try some mild polishing compound and step up to rubbing compound if needed. Then re wax and should be good to go unless the clear coat is going south on you.