It drives me nuts also.. Never really know for sure what size it is.. I'm pretty good at eyeballing size.. But I can't tell metric or standard just by looking at it.. So I'm always walking back with one of each
Ever work on '80's GM cars? Luckily, they used to put a dab of white paint on the metric hardware. It was because of the Canadian influence on the vehicles that were built north of the border.
We were all really good in our repair shop, but late in the day, and poor lighting makes a 5/16-18 bolt look a lot like 8mm 1.25!
I have a question to all of those who think we should go metric: Will we go to a metric calendar? How about a metric clock? Let me know how that works out for you!