Stainless steel bolts are regularly used in outboard motors which are primarily made from aluminum castings. When operated in salt water the opportunity for corrosion is many times greater than what we see on the road. The use of an antiseize is a good idea as it will lubricate the fastener and does not easily wash out. The Stainless steel used in corrosion resistant fasteners does not typically have as high a yield strength as carbon steel. A 300 series stainless steel has a yield strength of 100,000 psi which is equivalent to a grade 5 steel bolt. A grade 8 alloy steel fastener has a yield around 150,000 psi. Very high quality bolts have yields in the 180,000 psi range.
Most, if not all, steel fasteners are plated with cadmium, which gives them the silver/gold appearance or are treated with an oxide giving them the black color. These plating materials act to prevent corrosion but also act as a lubricant with installing or removing the bolt. Stainless bolts have no coating and are therefore more prone to galling. You never want to use stainless on stainless without an antiseize.
I would have no problem recommending stainless in any application into aluminum or for that matter steel, where fastening requirements could be met with a grade 5 bolt. I would be careful when using them on exhaust manifolds due to the heat and resulting expansion of the header flange. As the flange heats up and expands and could likely stretch the bolt, resulting in loss of torque and clamping loads. An alloy steel fastener would be better suited for this application.
