typically no better in fighting corrosion.
fasteners in both us and metric are coated with zinc dichromate. zd can be in most any color of clear (silver) yellow and they also have green, red i believe black as well.
clear (silver) is used on grades 2 and 5 us and 8.8 in metric.
yellow is used on grade 8. you will also find black oxide color on b7 rod and some bolts and socket head cap screws.
for corrosion resistence you need to go to an 18-8 material which is stainless steel. the next step up from 18-8 is 316 stainless for corrosion. the only down side to stainless is the strength of the bolt. if you need to use "BRUTE FORCE & IGNORANCE" on the bolt stainless isn't as tough as the treated rod or bolt.
on my cars as i replace fasteners i use stainless steel on the metal type (like a wood screw) on the metric machine screw i have to use the clear zinc coating because that's all i can get locally.
1972 350sl Red/Blk 117k
1988 420sel charcoal/Blk 140k
1987 420sel gold/tan 128k
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