Big bump for an old thread.
We had an partial loss of oil in MGB a few Days ago.
Oil filler cap O-ring failed/ wrong mounting wich caused the oil to dissapear that way.
One hour of flight since oil filled it lost 7L (out of about 20L?) and the MGB main pump pressure started dropping with a resulting short 'flash' warning MGB C / MGB COOL -warning.
The warning iluminated just Before landning, looks like it at least would have gotten to a MGB C/ Cooling problem if the flight had been longer.