I used metal degreaser on my aluminuim panels before sealed and fitted them to the my chassi.

The instructions said to spray on wipe and and wash with clean water prior to painting.

Given I was'nt painting I ignored the wash with clean water. Over the past couple of weeks my alloy pannels have dulled and are oxidising. Have spent most of the day washing them and then metal polishing them. I realise most will be covered in the final build but for now seeing all the hard work I have put in to make the panels and keep them scratch free its just anoying.

Thought I would pass on something else I have learnt...

just use brake cleaner, cleans anything you don't want from anything you do want, without damging anything you do want.