You could always boil up a pot of Cosmoline and restore that factory sludge in the core of the links... but short of that, you have options.
Personally, I really like ProGold's ProLink. A light oil that really does wonders for chains if applied often (200-300 miles). It is the "go-back-to" chain oil for many. On particularly bad days, I might wipe and re-oil after the ride. It all depends on the grit I pick up from the bike lanes.
But for lousy condition, a heavier oil like Phil Tenacious Oil which is simply a thicker oil with good adhesion. You either love the stuff or hate it. Here are some reviews:
The problem is not neccesarily the condition inside the links. A lot of grit mixed in with wet oil can wear your drivetrain out prematurely rather than the chain. It is a tough balance. I'm pretty confident that the lighter oils are doing their work inside the chain even if the outside is looking a bit shabby.