Owner's Manual
Page 328
At least every spring, flush these are not removed, accelerated corrosion (rust) can occur on the underbody parts such as fuel lines, frame, floor pan and exhaust system even though they have corrosion protection. Airborne pollutants can falhpon and attack painted surfaces on the underbody....forms: blotchy, ringlet-shaped discolorations, and small irregular dark spots etched into the paint surface. Dirt packed in the paint job causes this, Buick will repair, at no charge to the owner, the surfaces of new vehicles damaged by this for iceand snow removal and dust control can collect on...
At least every spring, flush these are not removed, accelerated corrosion (rust) can occur on the underbody parts such as fuel lines, frame, floor pan and exhaust system even though they have corrosion protection. Airborne pollutants can falhpon and attack painted surfaces on the underbody....forms: blotchy, ringlet-shaped discolorations, and small irregular dark spots etched into the paint surface. Dirt packed in the paint job causes this, Buick will repair, at no charge to the owner, the surfaces of new vehicles damaged by this for iceand snow removal and dust control can collect on...