Letter 42074

Corrosion resistance of aluminum polish [Virginia] 

August 29, 2006

Hello
I'm upgrading the exhaust of my 2004 Grand Marquis. I'd like to prevent the new pipes from corroding so they will last as long as possible and retain the aesthetic shine without maintenance. I've been considering sending the pipes to a shop to be polished or chrome plated. My question is: Does aluminum polish offer any corrosion resistance? especially against road salt? I know the triple chrome plating offers corrosion protection but don't want to rule out the possibility of polish.

Guy Bissonnette
consumer - Springfield, VA, USA

Chrome plated exhausts will reduce corrosion from the outside (i.e. road salt, etc) but a great deal of corrosion comes from the chemicals in the exhaust, moisture, etc inside the pipe. Further, in certain "hot zones" chrome plating will tend to discolor. If you want to coat the outside of the pipes I would suggest getting a high temperature powder coat (some look almost like chromium) applied. But really, from personal experience I have had modern OEM exhaust systems go over 200K miles with no corrosion (most components are ss).

Gene Packman
- Great Neck, NY

Maybe your car's exhaust pipe is stainless, and the tailpipe is aluminum-clad steel. Not much benefit, and rather difficult, to plate either.

Most aluminum polishes are acidic and remove the surface oxide to make the metal shiny, leaving an oily film. Not good for aluminum-clad tailpipes, which depend upon their surface oxide for protection. An initial polishing & buffing to make the surface very smooth might help, though. Degrease afterwards.

Ken Vlach - Goleta, California

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