My old Mercedes 300 turbo-diesel has a good sized oil cooler (especially for a 183 cu. in. engine) that is supplied from the oil filter housing pressurized, and returned to a different part of the housing. From there it supplies the galleys and a separate external pipe that runs directly to the turbo. The hot turbo oil is drained directly into the pan via a tube of larger diameter than the supply pipe. No pressure after it's "done", just a wide open drain.
Along with the cooler ports, turbo port and bypass pressure relief valve, the filter housing also has a thermostat that begins to open the cooler feed line at 95°C (203°F), fully open at 110°C (230°F). Oil that is too cool is not good either.
The pistons are cooled by nozzles that squirt a stream of oil into one end of an annular ring cast inside the top of each piston. The oil just exits at the other end of the ring. The factory engine manual states failure will surely be imminent should one of the nozzles become plugged or it's orifice damaged.
On top of all that, the little engine also took 9 1/2 quarts to fill halfway between dipstick marks when I recently finished the rebuild. Could have put in 10. Takes 7 1/2 qts. at oil change, could put in 8. As in 2 gallons.
You could say the engineers took the oil system in this little engine very seriously, which probably goes a long way to explaining why they can last so long. Big cooler, big filter, big pump, big journals, lots of oil.