Clean it up, then coat with this product: (note, you will not find anything better at protecting than this)
SYNTHETIC, WAX-BASED DRY CORROSION PREVENTIVE COATING Conforms to the scope and intended use of MIL-C-16173D (Grade 1)NSN 8030-00-62-6950NATO 6850-66-132-5848NATO 6850-55-132-6099 The world's most effective and long-lasting corrosion inhibitor spray, MaxWax™ is a tough, synthetic wax-based...
www.corrosionx.com
There are many products that can slow corrosion. Fluid film and others. Corrosion X makes an array of products that are used professionally in the aviation world. They are superb. However, one product stands out as "flat out amazing" and it's "Max Wax". It sprays on or brushes on relatively thin, soaks into mild corrosion, encapsulates it, and then dries to a waxy coating that does not attract dirt.
It's NOT the same as Boeshield, or LPS-3 or any of the other products that have a waxy or thick consistency. Max Wax is top tier stuff and every bit as good (maybe even better) as the more expensive Ardrox AV-30.