Why does the temperature of the oil in my car keep rising when I am driving?

Why does the temperature of the oil in my Volkswagen Touran keep rising when I am driving?
Presumably it's a diesel. If so, the engine oil lubricates and cools the turbo bearing and if the flow is restricted by coked up turbo bearing oil feed and oil return pipes the turbo will not cool properly and will overheat the restricted flow of oil through it.
Answered by Honest John on

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