Oil fan switch

I'm installing an external oil cooler with fan. I want to install a thermostatic fan switch, what's the best way to wire it?

Thanks in advance

 

This may help you mate ,?(me , dunno ) but I just googled "wiring a thermostatic fan switch" and seems to be quite a bit of advice re same.might help/something to chew over.best wishes .

 

Is it necessary given the air flow in the engine bay already?