Patch Lube...and lots cheaper than the pre-fab stuff. The below is the "Moose Snot" recipe from over on www.muzzleloadingforum.com. I use more beeswax...50/50 with olive oil actually and then add the Murphys an ounce at a time until it looks right.
A mixture of Beeswax, Olive oil and Murphys oil soap with the ingredients added in that order.
Beeswax 2 oz. Olive Oil 8 oz. Murphy's Oil Soap 1 oz.
Heat the beeswax in a coffee can submerged in an inch of water at the bottom of a bigger pat or pot (double boiler). Add olive oil when the wax is melted. Stir. Add Murphys and stir rapidly. Lift the can with vise grip pliers and pour into waiting tins. You should obviously increase the ratio of oils to wax for colder climates.
Pipe tobbaco tins work very well for storage and seal well enough that the moisture won't evaporate over time. BTW, this mixture also is a pretty good shoe polish or moustache wax for those of us who sport the big mediterranean handlebars.