[
QUOTE=Patrick;267421]From http://en.wikipedia.org/wiki/Engine_oil:
In engines, there is inevitably some exposure of the oil to products of internal combustion, and microscopic coke particles from black soot accumulate in the oil during operation. Also the rubbing of metal engine parts inevitably produces some microscopic metallic particles from the wearing of the surfaces. Such particles could circulate in the oil and grind against the part surfaces causing wear. The oil filter removes many of the particles and sludge, but eventually the oil filter can become clogged, if used for extremely long periods. The motor oil and especially the additives also undergo thermal and mechanical degradation. For these reasons, the oil and the oil filter need to be periodically replaced. While there is a full industry surrounding regular oil changes and maintenance, an oil change is a fairly simple operation that most car owners can do themselves.[/QUOTE]
Looking at my car since 35.000 km (22.000 miles) no oil change, oil is thin same as new one, oil filter has been changed at 30.000 km (the oil filter was not damaged nor clogged but i changed it), the car is running perfectly, somehow i dont believe i really dont trust these sayings that the oil brakes down and we need to change it as often as they say.
Anyway I will test my car and even if it brakes down i dont care i want to see for how long it will go without oil change. I strongly believe that the engine will run up to a milion miles with the same oil, full synthetic.
My belive is that the engine gets destroyed and wears out only if driven reclessly, inapropriate oil in the engine (worse than driving reclessly), low quality oil (mineral or half synthetic), if coolants leaks in the oil, bad air filter (clogged) needs to be cleaned with air pressure gun every 1000 miles (i do it often than that)(especially diesel engines need more air than gasoline engines)), and other things that will go out of normal operation like no coolant or bad fan so the engines overheats.