If you are trying to remove bad surface oxidation and contaminants, I would not use anything rougher that 1000 grit sand paper.

200 grit will simply remove the paint.

My dad was a car painter when I was a kid, and I did a lot of color sanding.

1000 grit is the roughest sandpaper I've ever seen used to color sand.

I helped a friend color sand his truck that was repainted, and we used 1500 grit to remove bad orange peel.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".