Not sure how difficult it is to get Dawn Norm but Amazon sell it.
I've also heard Simple green from Bunnings works but some say it will etch the alloy and Dawn works just as well but won't eat into the alloy.
Possibly with Simple green you need to clean afterwards as that's what they recommend ,there is a Simple green wheel and tyre cleaner that would be better on the alloy.
Unfinished, uncoated or unpainted aluminum cleaned with Simple Green products should receive some sort of protectant after cleaning to prevent oxidation. Simple Green has also developed break-through water based cleaners that are safe for use on metals, plastics, rubber and high tech alloys.
