Originally Posted by m6pwr
The Ford research mentioned in the SAE paper shows maybe a technical phenomenon, but as a practical matter, is it possible that shortening the oem oci can significantly shorten engine life? I seriously doubt it. But on the other side of the coin, I've yet to see any credible research (SAE, ASME, STLE) that shows shorter oci's (shorter than what the oem recommends) prolongs engine life.
This is the grey area.
Everything I have seen, including this paper, points to oil being its happiest between roughly 3,000 and 12,000 miles - exclusive of fuel dilution common in DI engines, acidic blowby combustion byproducts, etc. Unless these other factors are also measured and put in perspective we are pretty much guessing.
There is no credible reason to change synthetic oil at 3,000 miles. There is similarly no credible reason to wait until 15,000 ("BMW tells me to" is similarly unsupported, but for anecdotal insistence and supposition).
BMW's sesnsors, while neat, are apparently set to detect disasters only. Change the oil at 13,000 and the system will say change the oil at 15,000 - even if the mileage has been put on within the last six months, time is thus not a factor.
Bottom line: Don't sweat it. Change the oil when you feel like it within the above parameters. We don't have any objective, non-controversial data to indicate otherwise.
Put your saved mental energy into some good driving classes.