Borderline pumping temperature
Even at a very low start temperature, the oil must remain pumpable; the oil pump should be able to suck it up and transport it. Sufficient oil must therefore flow from the oil sump through the oil screen to the oil pump, and no air can be sucked up in this process.
If this is not the case, deficient lubrication can occur and cause serious engine damage.
Engine oils must reach a specific borderline pumping temperature depending on the viscosity class, at which the oil still flows freely to the oil pump.
The associated viscosity limit value is 60,000 mPa·s.