5VZ-FE Cooling System Question

I have a slow leak in my cooling system and I think I may have found the culprit but unsure if it really is because all diagrams show this hose leading from my thermostat housing to the engine oil cooler.
Is this a water hose (arrow pointed to it) or oil hose in the diagram below?



Here is a closer view of the thermostat housing where it shows with and without oil cooling but the hose clearly comes directly off the thermostat housing which, to me, indicates it is a water hose. The fact that it leads to the oil cooler is what is throwing me.



I'm not a professional mechanic so forgive the ignorance and thanks for any clarifications!

 

Its a oil cooler hose, coolant travels thru it.

 

That hose you are pointing to has coolant running through it. comes down from the heads, through channels in the block, out that pump, and into the thermostat housing.

 

Thanks for the clarification...
Logic told me it was a water coolant hose since it attached to the thermostat housing... the fact that it attaches to the engine oil cooler threw me off.

Thanks again!

 

The oil is water cooled, they don't mix tho, there's a coiled tube in the oil cooler that the coolant circulates thru.

 

^ what he said

 

Well after all that and I believe it is indeed a water pump leak.... Fun times! Thanks for everybody's help!