The word ᴱQ. millo “oil” appeared in Early Noldorin Word-lists of the 1920s as a cognate of ᴱN. bliw, both derived from primitive ᴱ✶mḷgo (PE13/139). In the Qenya Lexicon of the 1910s the word for “oil” was ᴱQ. ilma derived from the early root ᴱ√ILI “shine oily” (QL/42).
Neo-Quenya: For purposes of Neo-Quenya I’d retain ᴺQ. millo for “oil” from a Neo-Root ᴺ√MILIG, where lg became ll (PE19/93). However, I would assume a stem form of millu- and a primitive form ✱mil’gu to better explain the final w in ᴺS. blîw “oil”.
A word for “air” in Early Qenya Word-lists of the 1920s (PE16/142), probably based on the early root ᴱ√ILU “ether”. Later ᴹQ. Ilma was used for “Starlight” (Ety/GIL; LR/205).