The general suggestion is for Zetec oil to be 115 Deg, with water about 90/95.
This is what Eugene runs, with a rise in temps when really going for it...
I am thinking of an oil cooler, with thermostat, as when really 'making progress' (thrashing the nuts off it!) the oil temp can rise to over 120/125, but with no loss in oil pressure, so not too worried - but would like to bring it down a bit.
I also have the alloy rad.
(But, it is very unusual for the oil to run colder than the water - are you sure about that???)