Just remember to constantly keep them sealed and weather tight. I used to use the lubricant spray, but would just wash off in rain or during washing, was constantly reapplying every week or more. Eventually the threads just corroded and the spring platforms stuck solid. Had to go back to KW in Germany to get refurbed (free of charge though). KW coilovers are stainless steel, apart from the polo ones as like all polo coilovers use modified hubs. They are just zinc plated (think), which soon gets taken off from the spring platforms being wound down the threads.
I would assume most other polo coilovers are the same...