Virtually all refrigeration products are driven by a compressor (motor). This motor, compresses the coolant which is a gas, and releases it into the evaporator (cold pipe). It is this expansion of compressed gas that creates cold, following Boyle's Law, Charles's Law and Avogadro's Principle which state that temperature is directly proportional to pressure and volume.
The compressor contains oil, just as your car engine does. As the cooling system is a loop linked to the compressor, when the unit is moved, particularly if it is tilted, the oil can 'fall' into the evaporator. If the compressor is run, whilst there is oil in the evaporator, this oil can cause problems/blockages within the evaporator.
All refrigeration products should be left to settle before switching on and the design of the evaporator dictates how long a unit should be left for. EuroCave evaporators are long and thin, running top to bottom within the rear wall, so plenty of time should be left for any oil to drain back into the compressor.