Damn, It seems that the algorithm isn't all that complicated on the megane either. When up to temp the oil temp is always exactly 10 degrees hotter than coolant. As soon as one changes a degree so does the other. Not sure if this is the case when colder. Although the oil never gets below high teens / early twenties and I only drive the car at the weekends, so has plenty of time to cool. Dunno if thats right or not.