Mazda 6 Service Manual: No.5 engine stalls-after start/at idle

No.4 hard to start/long crank/erratic start/erratic crank

No.6 cranks normally but will not start

Other materials:

Mazda 6 Service Manual: Outside Temperature Display (Without Multi-information Display)
When the ignition is switched ON, the outside temperature is displayed. NOTE Under the following conditions, the outside temperature display may differ from the actual outside temperature depending on the surroundings and vehicle conditions: Significantly cold or hot temperatures. Sudden ...

Mazda 6 Service Manual: Inspecting Coolant Level
WARNING Do not use a match or live flame in the engine compartment. DO NOT ADD COOLANT WHEN THE ENGINE IS HOT: A hot engine is dangerous. If the engine has been running, parts of the engine compartment can become very hot. You could be burned. Carefully inspect the engine coolant in the coola ...