Yes, with Fire or Light Oil applied, Split Shot actually takes on different properties.
When Fire or Light oil is applied, the 3-piece Faron set is not recognizing the skill as Split Shot anymore.
There's definitely a bug in the coding, and this was brought up at U7 when they made it where Blood Arrow and Split Shot were affected by Oils, but there still hasn't been anything done about it.
My other Warhorse is a Fleet Tactical Escort Retrofit,[I] Defiant-Class[/I], [I]U.S.S. Say My Name[/I], NCC-93144