For my road bike - Pro Link. I find that I can easily get 2000 miles out of a chain when I use this lube frequently. This lube doesn't gunk up the chain as mush as other lubes I've used

For my mountain bike - chainsaw bar oil. You can get this at any hardware store. I heat it up before applying it and let it set up for a few hours after application. It not only lubes the chain innards, it also forms a barrier to prevent dirt from getting into the innards.