and total luck that the fire crews happened to be there.
Apart from one statement, much earlier on, (which many people have jumped on as fact and quoted ), I have seen no verification that the fire crews were out and about for other than attending this incident. The telemetry from the aircraft would have been monitored by the SQ engineers as soon as the aircraft turned back, if the fuel leak was spotted then, in all probability ATC were advised and would have taken the decision to have fire services standing by, regardless of what the crew said.
We have no idea at all what communication there was, by various means, between the aircraft and SQ Ops and Engineering, as well as ATC, so much of what has been posted here is wild speculation.
Reply Machinbird: A two hour return flight after an oil temperature warning, is aremarkable feat!
Most aircraft engines allow for a reduction in thrust to maintain oil temps. and pressure
within limits, if it cannot be kept within limits then it must be shut down.