Regarding using 30 weight oil - my advice would be to torque them to the same final number (80 ft-lbs, if my memory is correct). However, I would torque cycle each nut at least five times to condition the threads. The big advantage of the ARP lube (if you believe their test results) is that you consistently hit the same preload for the same torque without needing to torque cycle several times. With oil, you need torque cycle many times to get a consistent preload at a given torque.
Check out this page, and click on page "4".
http://arp-bolts.com/pages/arpultratorque.shtml Notice that the ARP lube and oil give the same results, but only after the oiled fasteners are torque cycled over five times.
Regarding re-torquing - this topic has been beaten to death on this board. Some knowledgable people say to re-torque (often with different procedures), and other knowledgable people say it's not necessary.
When I did mine (ARP studs, ARP lube, 9441 gaskets), I re-torqued after running the engine a couple of times. All I did was put a wrench on the nuts and turn them in the clockwise direction - I did not loosen and then re-tighten them. So, maybe this was more of "checking torque" than "re-torquing". Even just doing this, some of the nuts turned a little before reaching 80 ft-lbs. This makes me think that some things "settled" after I ran the engine a few times.
BTW, of course the factory didn't re-torque. It would take too much time and cost too much money to re-torque every engine's head bolts after heating-up the engine. What the factory probably did do was use a "multiple" to torque all of the head bolts simultaneously rather than one-at-a-time like we do. This usually gives a pretty good result - at least it did when we developed head bolt torquing procedures on a new engine I worked on at another OEM. When we developed the torquing procedure for the service manual, which of course torques the bolts one-at-a-time, we could never quite get the preload on all of the bolts as consistent as the factory "multiple" could achieve. But, it was "good enough" for a normal engine under normal usage.
Here's some links - after you read them, decide for yourself what is best for you! A search with terms "retorque ARP studs" will turn up a lot of results.
http://turbobuick.com/forums/threads/retorquing-heads-when.53461/
http://turbobuick.com/forums/threads/headgasket-installation-with-studs.309697/ (this one is a sticky)
I'm sure there are others...
Good luck,
