For heavy, grimy deposits I remove as much grit/grime as I can with a putty knife/other scraping tools followed by your choice of degreaser and a spray at the car wash.
Simple green is probably the least reactive with aluminum. Be careful with Super Clean/Purple Power as it will etch aluminum if you leave it on too long. Oven cleaner is a great degreaser (it's caustic lye in a spray can), but you can't leave it on aluminum for more than a few minutes.
I would clean the barbs off that nick with a file and leave it alone beyond that. It's not a pressurized seal and not a perfect seal from the factory to begin with.
Simple green is probably the least reactive with aluminum. Be careful with Super Clean/Purple Power as it will etch aluminum if you leave it on too long. Oven cleaner is a great degreaser (it's caustic lye in a spray can), but you can't leave it on aluminum for more than a few minutes.
I would clean the barbs off that nick with a file and leave it alone beyond that. It's not a pressurized seal and not a perfect seal from the factory to begin with.




