Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Radius
PRIM_OILTANK_RADIUS
Parameter: Height
PRIM_OILTANK_HEIGHT
Parameter: Height Segments
PRIM_OILTANK_HSUB
Parameter: Cap Height
PRIM_OILTANK_CAPHEIGHT
Parameter: Cap Segments
PRIM_OILTANK_FSUB
Parameter: Rotation Segments
PRIM_OILTANK_SEG
Parameter: Switch to Updated Oil Tank
PRIM_OILTANK_SWITCH_TO_UPDATED