Tightening bolts to a certain torque is meant to stretch the bolt slightly, not past the point of permanently distorting the bolt, but up to the point the bolt will return to normal length when loosened. Using a bolt, a stud with a nut, using oil on the threads, using a moly lube on the threads, using nothing on the threads, all effect the amount the bolt or stud stretches with a certain torque put on it.
In other words, it takes more torque to stretch a bolt put in dry to give it the same stretch that it has if put in with moly lube or oil on it.
In the case of rod bolts, it is important to stretch the bolt to the manufactures recommendation so the rod cap doesn't actually try to pull away from the rod at high rpm.
The best way to tighten rod bolts is to measure the stretch and pay no attention to the torque required to get that amount of stetch. If properly stretched, the bolts won't come loose.
See ARP's excellent article at
http://www.arp-bolts.com/pages/tech/fastener.html
I made a stretch gauge using a dial indicator when I did my engine. Worked great.
Also see
http://www.arp-bolts.com/media/pdf_files/RB_16-18.pdf
In ARPs old catalog, they say about rod bolts:
"If a bolt is installed without sufficient preload (or pre-stretch), every revolution of the crankshaft will cause a separation between the connecting rod and rod cap. This imposes additional stretch in the bolt. The stretch disappears when the load is removed on each revolution, or cycle. This cycle stretching and relaxing can cause the bolt to fail due to fatigue, just like a paper clip that is bent back and forth by hand. To prevent this condition, the bolt's preload must be greater than the load caused by engine operation."
As for thread lockers, they are excellent and I use them on lots of things, but usually not rod bolts. I've never had one come loose.