> > bolt and a grade 8 with 6 lines, but neither have a manufacturer marking.
>
> (Doesn't a Grade 8 have _5_ lines?)
Actually, no. Grade 8 hardware has 6 lines. They are also commonly
plated with yellow cadmium, making them easy to spot (though this
isn't a requirement). Unmarked bolts indicate common hardware-grade
(Grade 3 or less, I believe). From what I've read, Grade 5 is
considered the minimum strength for automotive use, though other grades
are used depending on the application. The key seems to be to use a
fastener that's at least as strong as the one the manufacturer originally
used.
Regards,
Patrick
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