If you walk into a hardware store or nut and bolt supply and buy stainless nuts and bolts, you are buying crap: cheap, nasty and quite a bit less strength than good old grade 5. If you want to go stainless then go to a proper mil spec supplier. Always use copper anti-seize as stainless nuts and bolts easily gall their threads, even under light loads. Frankly good old plain jane grade 5 and grade 8 is a much better choice. If corrosion is an issue, coat the threads with copper anti-seize. I had no seized bolts or nuts when I disassembled my S1. Not bad after 40 years and minimal care when assembled at the factory.