I used Mobile-1 oil in all my cars, they all last 20 years still not consume oil. I also change oil every 5000 to 7000 miles, depends on how hard I was driving for that period of time. Despite Mobile-1 oil I brought saying 12000 miles, I don't use up all its lubrication abilities before changing oil. For my turbo engine Mercedes, I use 0-40 European Formula Mobile-1 oil, even living in hot southern California, for it could easier to pump to different part of Engine. I do not use that green Mobile-1 oil, since that is not formulated for European cars.

 

 

Would you like to know that in my country (Greece), L.E. 15W40 which was used in a bus, when tooked sampling oil from engine at 140.000 km, the oil did not replaced but it continued lubricating the bus, I don't know for how many km more? The only change was the filter that was replaced some times, don't know how many.
The additives from LE oils are unique, and you'll not find them in any other oil all over the world. Also as I wrote above, they're 100% made from parafinic base oils, which means that quality is the best that can be, and lubricating is excellent as they are natural not synthetics with the problems that synthetic have in lubrication.
More, ALL oils DO NOT HAVE max or min periods of replacement, it depends of the use of them. It's different to use an oil in a car and different in a heavy duty truck. Different on an old engine vs a new one, different on bad conditions as bad air with dust or other dirty than a clean air place, could reffer a lot more........
The best way to check if oil needs to be replaced, is by taking sample from the engine and send for OIL ANALYSIS in a company that can do it.
Personally -because I had gas station some years ago- was send a sample from an oil called I think CITGO 20W50, sampled from a VOLVO FH12 after 20.000km of use. The results shown that it probably could do 10.000km more before replacement, because -as technical's said- "the engine was in very good condition and the load was not big for the truck".
The truck with it's trailer was travelling at full load from Greece to Italy, but as they explained to me "this is NOT MUCH STRETCH for track's engine the fact that it was just travelling many km's on highway".
Also when I asked "why you advertising it for 20.000km on passenger car's" the answer was "because not everybody does oil sampling, not everybody has the knowlegement, and we MUST SALE products to survive, so we set a GENERAL limit that our oils CAN EASY TO ΜΕΕΤ".
That's all, any other I would be happy to help. Don't hear marketing, because companies need to increase sales every year, which means more money for them and a lot of bonus for members.

 

Oil lubricates because its large molecules. Under heat and engine pistons pressure, those large molecules would break down, thus oil became less effective to lubricate. That is why oil change is needed.

 

That's not the only reason as I wrote above, but if you want to follow your mind instead of what tests and technicals prove, then do as you want.
But you should answer why an oil does need to be changed in 10.000km and another one at 100.000km.
That's a big difference, don't you think?

 

Large molecules is dino , synthetic smaller and more regular .