Heh, I bet half the forum with air tools wasted money on those
You want a good oiler. Best to have it on its own port on the compressor so you have another port with clean air.
I bought a cheap Chinese oiler/filter/regulator combo. Regulator/filter started leaking within a few months. The oiler was tricky to adjust, either lots of oil or none in 1/16th turn of set crew.
I replaced the filter/reg with a Norgen and how have just ordered a Norgen Micro Fog oiler.
i got one free with an impact wrench its still in box .all my airtools just get 3 drops of 3 in one oil at start of use. then 3 at the end and a quick run through which lubricate the internal parts against corosion from moisture
Got a couple of those, one's never been used though. The other gets filled with a oil can, the lever/pressure type. Done in a few squirts. Does seem a bit free with the oil, but not too bad. CBA fitting the other one though...