A couple of recommended lubricants for the Flourocarbon (Vitone) O-rings is Dow Corning 55 or the Parker Super O lube.
I'm with Jacques, I like to use the Dow Corning Molykote 55 as I obtain exceptional results with this product.
Using the correct O'ring grease assures a good seal and goes beyond protecting the o'ring past the initial installation as opposed to using oil. The Dow corning 55 maintains the O'rings dynamic properties and protects it from the effects of aging/oxidizing degradation. If you simply use oil to assemble your O'rings it works but, simply put, it's not the best approach.http://www.anchorrubber.com/specialty/parker_o-lube.pdf
I know several of the members on this board know this already but just thought I'd mention it.
The trick to minimizing or preventing the case O'rings from being extruded or cut during engine case assembly is to fully seat the case halves prior to installing the O'rings with the correct nuts and beveled washers. Then one by one remove the case nuts, lightly lubricate the o'rings completly with the Dow Corning Molykote 55 and then slide on and fully seat the O-rings followed by installing the correct washers and torque away. Hope that makes sense.
There are definately several techniques and neat products out there in order to build and assure a nice dry leak free motor.