I have been really thinking about an additional perhaps new wrinkle for about a year. If your fuel supply system is really tight like when it was new. In cold weather the critical few first revolutions will receive full fuel discharges from the injectors.

Ideally the fuel pressure is held in the system till the next time you go to start the car. I suspect when new these cars where like that.

Now when not in good maintained condition I imagine the first few revolutions may just be the time the injection pump elements are just trying to scavenge enough fuel and may come up short enough. If so you have lost the opportune starting ability.

The valves being tight in the lift pump will be needed. Perhaps a pressure test and shut the engine down to see if the pressure bleeds off below the relief valves closing pressure remains.

I even considered the addition of another check value like the early volkswagon diesels had may not be a bad ideal.

Otherwise coming up short injected fuel quantity wise may mean at least a few revolutions may be needed even before the elements make enough pressure to even open the injectors. Or the amount of fuel supplied is just not enough to enable strong combustion even if they open.

The heavier thick base oil needs a strong series of combustions to overcome the drag when cold to get running. The engine is going to crank until enough fuel is present while the glow plugs maximum heat is dropping during the wait.

Also it would be easier on your battery and starter as well to improve cold starting ability to the maximum. This is really important for winter users in areas that need it. There may be other benefits even in warm weather. For example I notice a couple of my engines light off almost instantly. I know those engines are getting the right quantity of fuel in less than a second.

Now people could say it is because the compression is better. That may of course be true. By the same token you could have an engine with great compression. If it does not receive enough fuel to start almost instantly. It is going to turn over till it does. During this period you are rapidly loosing glow plug effect temperature and the starter is starting to slow a little.