Help needed urgent
 

Hi guys new member here and in despetrate need of help,we have a 2000 year grand voyager 2.5 turbo diesel,we keep getting oil in the water,i have took the water tank and pipes off as the previous owner said they had put oil the water tank by mistake,took everything off and cleaned flushed whole system but still getting it.
any body else think this is the oil cooler or head gasket?
where is the oil cooloer situated on the car?
help needed asap