© Lloyd

The same is true for any decent-quality synthetic.  And I'd guess that was a Powerstroke engine in that van - they are known for lasting that long, or longer.

Filtration is more important to longevity than the oil used.  Mount a second, low-micron bypass filter if you want to reduce engine wear.  The standard filter can only filter so well before it impedes oil flow, so there's a balance between capturing all of the contaminants and not restricting flow.  A bypass filter only filters a fraction of the oil flow at any given time, but it filters it really well.  After a certain amount of time, that fraction at a time adds up to having filtered all of the oil.  Stick magnets on the filters, as well, to capture any metal particles.

With a bypass filter and a quality synthetic, you can easily go more than 15k miles on any quality synthetic.  When you get to that point, what you typically do is take a sample every so often (interval determined based upon your engine and the use of the vehicle) and send it for analysis.  The company doing the analysis will return a report that tells you how the oil is doing, and lets you determine when it's actually time to replace it, rather than doing so on a set schedule.