Oil Temp, Engine Temp and Rad Temp

I got a little excited yesterday following a breakdown and set about a spending spree for the DRz, this included a vapor dash unit.
Nothing much wrong with the standard one other than it looks shocking and has a habbit of misting up over winter due to crappy seals.

Anyway, the unit comes with temp sensor which you put into the top of the rad, where the pressure release bolt is - This reading is then displayed in the top left of the unit when in use and a warning light on the unit flashes when the temp gets too high.

It also comes with a seperate dash panel with verious options for warning lights, inc an oil (I assume temp) warning light as it is on the standard panel.

If I've already a Rad temp sensor and warning light, is there much need to use the oil warning light as I'd prefer to use one of the other functions in its place.