This is from ebay Reviews & Guides
Stainless steel bolts are not stronger than ordinary steel bolts
This is clearly true for the majority of stainless steel bolts. Stainless steel in general has very little carbon, and because of that, most grades of stainless steel cannot be hardened by heat treatment. Stainless steel bolts are, in most cases, just slightly stronger than Grade 2 hardware store junk bolts, and in nearly all cases, significantly less than Grade 5. You do NOT want to use common-grade stainless fasteners in any application that would call for a hardened (Grade 5 or Grade 8, or stronger) fastener. ARP makes a fine line of stainless bolts that have a tensile strength of approximately 170,000 lbs per square inch. This is greater tensile strength than a typical Grade 8 fastener, but keep in mind that tensile strength is not the only measure of bolt quality/strength. Common grades of stainless steel may have reasonable tensile strength, but significantly less yield strength than a "regular" steel bolt--the stainless bolts are more "stretchy". Those ARP-made bolts are the ONLY stainless fasteners I'm aware of that are suitable for general use
Another issue with common grades of stainless steel is that the threads often seize ("gall") between the bolt and the nut. I suggest the use of an anti-seize compound, coupled to CAREFUL USE OF THE TORQUE WRENCH when tightening stainless steel. You MUST use a torque setting on the wrench suitable for the mechanical limits of the fastener, as adjusted for the reduced thread friction inherent when using a thread lubricant like anti-sieze compounds. As a rule of thumb, and unless the manufacturer says otherwise: Consider a stainless steel fastener to be capable of Grade 2 torque loads, and then adjust the torque DOWNWARD by 20% because of the lubricant properties of the anti-sieze.
Example: A common 304 (A2) 3/8-16 stainless bolt should accept the same torque as a 3/8-16 Grade 2 bolt--only about 20 ft/lbs. But since you've lubricated the threads with anti-seize compound, you'd reduce the torque by 20%, for a torque-wrench-setting of 16 ft/lbs. That is NOT VERY MUCH for a 3/8 bolt!!! There are stronger stainless bolts--some but not all 316 alloy bolts will take almost but not quite Grade 5 torque specs, but again you must adjust downward when you use anti-sieze. If you're used to working with hardened fasteners (Grade 5 and Grade 8) you won't believe how little torque is the maximum acceptable amount.