Behaviour, and degradation of lubricant in the ring belt.
Interesting paper looks at how long lubricants (and how much) hang around in the ring belt, and their movement back to the sump, or into the chamber.
Looks then at how the oil degrades, using a temperature controlled sump of 70C (and entirely separate valve train lube system) to ensure that the degradation/oxidation in the sump is controlled almost entirely from what's going on around the rings.
Really interesting measurements of residence time in the ring belt, versus how long the same oil stays in the sump...e.g. 0.41ml oil flow per minute per cylinder INTO the ring pack, 0.36ml oil flow per minute per cylinder out of the ring pack (0.05ml/min per cylinder goes missing - translate that in the 4 cyl version of the test engine, and 0.2ml/minute...946ml/qt, means 4,730 minutes per quart of consumption excluding dilution reducing the dipstick effect...or 4,730 miles at 60miles per hour for a quart consumed).
It stacks up with previous studies that I've read showing a concentration of additives in the ring belt, as the oil goes missing somewhat.
Rate of supply/drain back means that there's probably nearly never a truly "dry" start, and even 10 seconds of "starvation" after a start is unlikely to run the ring pack dry.
Interesting what sort of temperatures the ring belt runs at, and for how long the oil stays there...Noack in this region is significant, but doesn't mean 10% of your sump evaporates in an OCI.
BTW, engine is Vauxhaul based FWIW.