Evening guys, start of the story, my dad drove up to the Midlands last Friday from Cornwall, I commented that his car (05 x type Sport D) didn't sound quite right, he thought nothing of it and set off for home, 90 mins later he's broken down, he said the car over heated massively and just died, his expansion tank is full of oil and also there are brown sludge spats all over the engine bay, I believe it to be head gasket failure but a mechanic who lives next to me says it's also symptomatic of oil cooler failure, I know nobody could answer for definite without seeing vehicle, but is he right? What is the likelihood of oil cooler failing?