[Trevor Booth]

if you get the correct S/S bolt it is equally as good as a SAE grade 5 but can have superior tensile strength. Some S/S are heat treatable and are typically used for exhaust manifold studs, head studs. I have used them for years with no failures but I make my own with rolled UNF threads not machined threads. Some S/S are precipitation hardened and are used for specialised aerospace and aircraft parts and fasteners. The ordinary off the shelf marine S/S bolt is usually a machined bolt and thread,and in most cases 316 grade. Apart from the fact that they have a course (UNC) thread, the machined thread weakens the bolt more so than a rolled thread. You would not use these bolts in a single shear (cantilevered load)application. MIl spec or AN aircraft bolts are not necessarily better than an SAE grade 5 unless you are familiar with them and what bolt to choose. The big difference is a guaranteed consistent quality and strength with superior plating. If you use a vehicle in competition you should replace all critical bolts on a regular basis. Personally I would not go to the extra expense of MIL or AN bolts. You can EN plate ordinary Sae Gr5 bolts at a fraction of the cost if you specifically want corrosion protection.