Lead additives are a good idea but not really necessary because we are not driving our cars real hard or pulling trailers.
The length of the 5/16 bolt must not be too long or it can get hung up prohibiting the pedal to move as far as necessary.
I think I have a lock nut on mine for insurance but make sure the brake pedal has full swing.
Jack Bowser
C56B2198
Past Ownership 1991, 3206, and 1763
2006 Ford GT
2006 Cadillac XLR-V
427 Cobra
2012 Mercedes SLS AMG Roadster
1924 Dodge Brothers Rat Rod
Lots of Bowser gas Pumps