Red lead was a combination of two lead oxides. As Miller stated, it was used in machine shops as a cutting or dead center lube, and it was also used in thread sealants and as a pigment in paint and primers. Red lead was also used to mark steel before blue marking dyes were available. White lead was another form of lead also used as a paint pigment, and both were sometimes used in early engines as gasket sealants with soft copper head gaskets.
It is true that lard based cutting lubes will turn rancid in a short time, especially in warm weather. But they still use them today, and add a biocide to keep bacteria from growing in them. It doesn't always work so well, and the smell of rancid animal fat based soluble oil is pretty nasty. It soaks into your skin and is hard to wash the smell off. It also has the bad property of turning the insulation on electrical wiring on CNC machine equipment very brittle, which is why I learned to hate it... along with the disgusting smell. Sulphur alone is a good cutting lubricant, and it has anti-bacterial properties which is a reason it was mixed with lard to make sulphur-lard cutting oil.
None of this tastes anything like bear meat, but it is relevant for Lloyd who is considering using lard for flintlock patch lube. I think I will stick with my Thompson Center Natural Lube 1000 Bore Butter. It works great, and has a pleasing anise oil smell that doesn't seem to spook deer or other animals. Now, I'll bet fresh eggs or walleye fried in fresh bear lard would be interesting occasionally, although not so heart-healthy.
