Q: I need some high temperature engine components that can provide high strength (100ksi yield) to 1000F as well as oxidation resistance? Are molybdenum bolts good for that?
A: Though Molybdenum is excellent in high temperature environments its generally reserved for very high temperature vacuum application where no oxygen is present. In addition your on the edge of molybdenum strength range. A better material choice would be A-286 fasteners. They are actually made for high temperature oxidation resistance and offer about 111ksi in yield strength which is in your range. They also maintain most of their strength to 1000F and could go to 1300F which will provide you the high temperature fastener you need as well.