It does sound like rust proofing, which I did at new car dealers for a short time, yes very messy. We did under coating and the rust proofing, but as expected, it was a fast not fully covering everything job for an employee. Cars have tons of places that are not accessible. The only good way to coat a vehicle is before or during assembly, the manufacturer should do that. I had my 99 fully apart, so when the body was done and still off the chassis. I used 3M undercoat, three cans did all of it except the wheel wells, I ran out then.
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