RB Harter wrote: "It's animal fat . Eventually it will turn ."
I think that sums it up nicely.
Our ancestors used animal fat for many different applications: lubricants, waterproofing, preservatives, candles, cooking, bullet lubes, etc. They did that largely because …THAT’S WHAT THEY HAD.
I think we sometimes place a little too much nostalgia on old practices that were undertaken out of necessity rather than superior performance.
While petroleum was known in the ancient world and used where it was available, it was not widely available. Whale oil, in particular, spermaceti oil, was the best oil known to man at the beginning of the industrial revolution. It wasn’t until petroleum was exploited on a large scale that petroleum replaced whale oil as a common lubricant.
Animal fats can be rendered and purified to a point, but in the end, they remain animal fat. They have severe limitations as lubricants, preservatives, waterproofing, etc.; but when that is what you have – that is what you use. I do not wish to disparage our ancestors; they did outstanding work with what they had available. However, just because a practice is old, doesn’t mean it is the best practice.