Go to the local discount store and get yourself a big jar of white petroleum jelly. The stuff is sold here by tradenames such as "Vaseline." If you buy a big enough jar and have your hair combed right, maybe one of the clerks will flirt with you on the way out....
Anyway, white petroleum jelly is an easily-applied, tenacious, and very effective coating which needs not be very thick in order to work. Rub some into a swatch of cloth until the cloth is saturated, and then store this in either a lidded glass jar or a "ziplock" plastic bag --and keep this in your kit for occasional use when you think best.
A cleaning patch can be filled, but not to saturation, and used to rub the grease into a bore. Although one can shoot over this (which doesn't hurt with cast bullets), things go better with jacketed bullets if a dry patch removes most of the coating before shooting. It always is best to use the thinnest reasonable coating in a bore, just in case one forgets and shoots without dry-patching first.
I've used white petroleum jelly since 1953 and NEVER had a problem of any kind with it. It is cheap, plentiful, and useful for other shop needs as well.
Paladin