Originally Posted by MrPogle
True but I'm looking at this as a learning exercise. The car is telling me I can go 17000 miles between changes. People who know more about engines than BMW tell me that this is madness and that 6000 miles is right. That is a massive discrepancy and I am a big fan of Scientific Fact so I thought for the price of a tank of fuel I could get a few samples analysed and learn the truth (or at least my personal version of it).
Another member on here did this, can't remember his name, on a 335i. There was a lot of fuel contamination found anyway.
I get your point mr pogle, so why not just change it every 6 then? I do for personal satisfaction.
I'm sure the oil sample will show it is ok relatively, but the 17000+ interval is not aimed at enthusiast owners (who know it is a marketing tool), or about keeping the engine perfect in tip top condition, its about striking a balance between low maintenance for the masses and increasing warranty failure costs.
Most euro cars are designed on a 10 year / 300,000km non consumable parts life cycle (i.e engine, drivetrain etc) and that will be tested using the long service intervals, not saying the engine would be in a good state by then, but it should work.
People generally want long intervals, it sells cars, most don't care about the engine as long as it starts in the morning. So no manufacturer will risk that by quoting overly generous maintenance.
And they don't want the car to last forever of course!