Addl; Manufacturers add different color dye's to their oil for various vendors. eg; motor mfg 1, uses green, mfg 2 uses blue but, they are the same oil- just different color and perhaps different additives. Also, some different oils will mix- Mercury says that Hi Perf oil will mix ok with premium blend- green vs. light yellow would look light green. Anyway, I think OMC oil is blue.