"If you just want a good gun grease to keep your guns lubricated go to any hardware, farm supply, or Walmart and buy a can or tube of Lithium grease."
I used to use lithium grease, but I've since moved to moly greases. I find their lubricating properties to be a bit better, and most of the lithium greases I've used over the years have gone pretty stiff at lower temperatures.
I used to use something called DSX grease, which was a fluropolymer grease, but it tended to stiffen up REALLY badly at low temperatures.
I'm just about out of grease, but I'm hearing good things about Valvoline's SynPower Synthetic grease for a wide variety of applications. It's primarily an automotive lubricant, but it supposedly has great lubricating properties and excellent corrosion resistance.
Plus, a pound of it is like $9...
Oddly enough, that's about the price of an OUNCE of Tetra Grease...