I want to recommend a amazing aluminum mast cleaner/protectant I've used over the past 4 years.  Three separate riggers agree!  

I have my C36 #2164 (2003) alum mast cleaned annually.  Four years ago I hired a rigger for the job; he did an amazing job. I asked him what he used. He didn't want to tell me, replying "that's why you hire me". I poked around and saw the spray container and noted the name.  

Subsequently, during the following years, I've hired other local well-know/respected riggers for this annual mast clean job.  I asked each to try this product, and both were so surprised by its performance.  I've attached two photos.  

The product is Aluma Guard Spray Protectant.  Avail at WM  

Needless to report, my mast is just like the day it was installed new!