Despite the fact that every one of the various engines in the Eurovans use the same oil cooler, the oil cooler hoses for the three engines are all different. These are critical hoses and should be checked often. They can fail in the middle of nowhere. See these below. Choose your oil cooler seals and hoses by your engine type/model year. The five cylinder engines use only one oil coller seal. The VR6 engines use both an inner and an outer seal.
If you have found oil in your coolant, this cooler has most likely failed internally, and allowing the two fluids to mix. Not a good thing.......