I use all HHS taps some of which I acquired during my tool and diemaker apprenticeship between '56-'61 and they're still sharp.
For D2, D5, A2 and the oil hardening tool steels, a good tapping fluid is a necessity, but for the soft, low carbon steels used in gun making, I just use machine oil because it's handy. Don't get "torn" threads or broken taps from using machine oil....works fine.....Fred