Sox 6, I'm not sure where the quote above comes from, but this is the relevant extract from the RFM. It's the 2005 version so it was in place at the time of the accident. My bold emphasis.
If the MGB OIL PRES warning or the MGB OIL PRES caution and any of the following secondary indications of gearbox
failure are observed:
MGB oil pressure below 5 psi
Smoke or fumes in the cabin
Any subsequent hydraulic system failure
Progressively increasing power required to maintain flight
Unusual vibrations or noises.
6. Land immediately.
HC is correct - although both our events had some low pressure associated with them, they were not "loss of oil" incidents.