Guys,My E39 523i is 1996 make (11 years young) and thus far it carries over 210,000km mileage. I just got it 2 x months back and the engine is in good condition...(touch wood)...As the car has been well taken care of my opinion is just to continue maintaining it by proper and regular servicing and touching up on unreliable parts every now and then as and when required. But is there any specific criteria (mileage wise, years run wise etc etc) over time even with good engine condition, the engine needs to be overhauled?Wondering if i should just continue maintain it and get to the overhaul matter when the engine really fails.Please comment...thanks.