Bolts can stretch/sheer and are made to different specs so that they can sheer off or stretch/bend instead depending on the application. Follow the manufacturers instructions to the "T" using their parts if you can not source their equivalent. Heat cycles will loosen fasteners esp in moving parts and or go through heat cycles and over time can stretch reducing the applied torque. Bolts clamping two dissimilar or even blends of metals are far more likely to loosen/over stretch and fail due to different expansion/contraction ratios. Rechecking applied torque of those bolts is likely suggested at every x amount of hours and or after x amount of use after replacement. Remember that even the bolts holes and its threads will expand and contract when heated/cooled. A mild version of thread locker will help prevent fasteners from rotating apart during heat cycles, A fine tipped center punch may be used to mark the bolt/nut and a metal face to monitor fastener movement/loosening at a glance during pre inspections before use. Hope this info helps !
Here is my .02cents @capetrees.
Best to install at normal temps.
Torque wrench torque for sure on final torque.
Check with manufacturer on tightening procedures. Dry, oiled threads, or a moly paste on threads. These all have an affect on final torque values and fastener retention.
One other tip I might add from the manufacturer. Verify this isn't an initial torque with a final torque turn in degrees such as 60-120 degrees after initial torque install.
The old hardware should not of loosened easier from slight temp changes in working temps. Now with a torch that's a different story of course.
As you can see I'm anal on torques and proper direction of flat washers if any are used.