There's an oily smell that's associated with older airguns that I can't get enough of!
I was told the old oil was the same stuff as SAE30 and as luck would have it, One of our maintenance lads had just bought a gallon of the stuff for his 1970's VeeDub Bus, It was the wrong stuff so he gave it to me, I forgot all about it, It's still in the garage somewhere
The smell is sort of like a small machine shop!!
John