Your pictured oiler looks to be a reproduction made for the commercial market. I have a few in one of my parts boxes just like it.
Not sure I have ever seen an oiler marked in Roman Numerals?
Oilers made by International Silver were marked, II, IU, IW, IR, IN, ISP, IQ and IS.
SW oilers marked on cap, unknown maker, possibly Stanley Works?
BK marked oilers were made by Blake Mfg.
Poley Bros. & Verson oilers had a unique bullseye and arrow marking surrounded by their name as well as the words Precision Built.
South Korean oilers were marked SN over 76, KJ over 76. Korean writing over 77
Unmarked USGI oilers were made by Yankee Hill Machine (Vietnam era)