[rotorwrench]

It you find really old castor oil you will likely be able to tell by the smell. When it goes bad, it doesn't smell good. Mineral oil generally always smells the same like most mineral oils do. Glycerin does taste sweet. I still use it for internal mount sores. If it gets all brown and nasty looking then most folks wouldn't want to taste it.

Glycerin and castor oil will both go bad over time. Back in they day, a who die damper was inexpensive so folks would chuck them and buy new ones. By the time the cars were well worn, a lot of them had lost their dampers into the dustbin of history. They weren't really supposed to be rebuilt. Hell they didn't even have interchangable parts. Houdaille fit each and every one of them individually back in the early Ford era.