Oil or Wather Soluble Coolant?

Hi all, I work in a shop that uses all oil for coolant in our machines except one(a big cnc lathe), including our 2 swiss lathes. Everywhere else i've worked uses water soluble coolant, and I was thinking of trying to convince my boss to change the swiss lathes to soluble coolant. the oil smokes a lot and doesnt seem to give the greatest surface finishes...
I was wondering if anyone else has had experience with this issue and had any recommendations before I ask my boss about it.
thanks!