first time you washed your car that stuff was gone. as a former chevrolet dealer i know this as fact.
I would counter that when I cleaned up the front end and rear end on my 1968 ssrs 396/325 80K mile car I found that years of grease, road dirt, oil and dealer undercoating preserved tons of Factory (VN) applied graffiti.
Interesting Examples found:
Green dabs on rear axle centers.
Yellow dabs on the front disk brake wheel stud ends
White and Orange on the spindles.
Yellow on the tie rod sleeves
Large orange dab on the rear axel center housing
Drive line stripes
Now do not get me wrong,,, I have made a TON of mistakes on my car over the years and am slow to correct.
I do enjoy the details!