I don't know the particular temperature limit numbers for Subarus, but in general under-hood radiator fans run by two independent sets of logic. One is from the a/c system - the fans must be ON, when the a/c compressor clutch is engaged, regardless of the temperature of the engine, cold or hot. This is to prevent the refrigerant pressure/temperature from rising too high, which would blow out the high pressure safety valve of the a/c system (ask me how I know this). The other fan-driver is from the coolant temperature inside the radiator (not the engine). The temperature at the engine itself only determines whether the thermostat/thermo-control valve will allow engine coolant to flow through the radiator or not. It's when the radiator starts getting too hot, and only then, that the radiator fans will start running (if not already driven on by the a/c). This temperature where fans start I think is usually about 210degF (100C). Since the radiator and engine are sealed and can stand coolant pressures above 1 atmosphere, everything can still quite safely heat up further beyond that, up to something like 240degF, the point at which the gauges or warning lights declare an overheating emergency. This is why removing a hot radiator cap is so dangerous - while pressurized, it wasn't boiling, but when you take off the cap the boiling point decreases and suddenly you have a burning hot geyser of coolant coming out onto you. Another one of my "fun experiences" was having my electric radiator fan motor completely fail (seized) during a long vacation trip. This seemed at first a disaster, but it turned out that even in kind-of warm temperatures (New Brunswick summer), the car could safely be driven at any speed above about 10 mph without any radiator fan at all, and not overheat. A/C had to be off, of course. When we got stopped in traffic, all that was needed was to run the heater at full blast (your heater + heater fan acts exactly like your radiator + radiator fan, if you can stand it). We drove all the way across NB, NS, and out onto PEI and back to Moncton successfully as we waited for our parts to arrive at the dealer to fix the car. So it's pretty clear, if your a/c is off and you're moving faster than a walking pace, your radiator fans are likely not to need to be running.
In my XT, the upper center display can be set to show Oil Temperature digitally. Is this not an option for 2.5L non-turbo '17 Foresters? The owner's manual describes how to make choices of what to display on this screen. I remember this selection being confusing but it did work. This is not to say that oil temperature and coolant temperature are equal parameters; they behave quite differently based on my experience with various non-Subarus and my current Subaru. The radiator coolant heats up the most when you are stopped in heavy traffic; the oil heats up the most when you are going fast up steep and long mountain highway grades. But I do find that seeing a numerical readout of my oil temperature, day-in and day-out, is reassurance that my engine overall is happy, more reassuring than just seeng that neither the blue nor the red water temperature lights are lit up.
note, my above comments about driving around with no radiator fan only apply if you have NOT lost any coolant (no boilover, no leaks) yet.
