There is a really good anti corrosion treatment I have used. Forespar is a mast and rigging company. They have a few products for dissimilar metal corrosion issues.
Try Lanocote.
Quote:
LanoCote® works on these five basic principals: displaces water, absorbs corrosion, forms moisture barrier, penetrates and has high lubricity. LanoCote® prevents dissimilar metal galvanization. LanoCote® is extremely effective in preventing and stopping corrosion on all types of metals under all environmental conditions. Formulated to withstand salt water marine conditions, LanoCote® is particularly useful in preventing thread seizure due to all types of corrosion on boats and machinery. Applied during assembly, LanoCote® will greatly assist in easy dismantling years later. An example would be anchor shackles which are regularly immersed in salt water. LanoCote® also combats galvanization where dissimilar metals are fastened together, such as stainless steel fittings on alloy masts etc.
https://www.forespar.com/products/boat-lubricant-lanocote.shtml