Here to - I replaced all with stainless, much bettta.
H
Yep, I keep maybe 500 stainless cap screws on hand all the time from M4 to M10. Mostly M6 from 10mm up to 100mm long and M8 from 10mm to 50mm.
I had one of my car engines out before christmas and replaced every bolt on the engine, transmission and in the engine bay before it went back in. When I ordered replacement stock I worked out I'd used over A$300 worth of bolts.
Whenever I remove a bolt I replace it with stainless if possible. M10 are a problem as bikes generally use a fine thread and I haven't found a source of fine thread stainless socketheads.
The only thing I don't like about stainless is they're very hard, which makes them difficult to drill for lockwiring. Two M10x150 stainless sockethead bolts cost me A$27 last year to replace two engine mount bolts on one of my bikes
I'm really big on reducing weight but there just isn't enough weight in the bolts on a bike to bother replacing them with aluminium. There are much bigger gains to be made elsewhere. M6 bolts would be one of the last items I'd do, when I was desperately chasing the last few hundred grams.
And if you're regularly working on the bike you need to keep plenty of spares for aluminium bolts.
Some of the bigger bolts I make aluminium replacements for like the fork clamps and rear disc bolts.
These are my fork clamp bolts.