Schaeffers makes a line of excellent petroleum oils w/ moly, although I think their Supreme 7000, synthetic blends are probably their best value for the dollar. If you order this stuff in bulk you can get it for about $2.75/qt. The S7000 is about 30% PAO synthetic and has a very robust additive chemistry. Depending on the application, you can safely run change intervals of 7000-10,000 miles.
The S7000 is about the only synthetic blend (along with the Amsoil 15w-40 blend, "PCO") that is worth the money. Most off the shelf synblends only have about 10%-15% synthetic content.
TooSlick