Hey Guys
Though thermo is not my specialty, I am a mechanical engineer and I’ll chime in here. I also have spent years working with air cooled VWs where oil is a far more critical part of the cooling system. Others have touched on a lot of important aspects but I will add a few thoughts.
The condenser coil would be a bad idea in series with the radiator, as this would obviously severely restrict coolant flow. In parallel it should add some cooling capacity, but I think it would be minor, specially when you consider the decrease in delta T it creates for the primary core, its effect might possibly be similar to turning on the heater and the increased air flow from removing it might have just as much affect (as RedNed stated). As for placing it in series with the heater circuit, most cars (I haven’t checked the subie yet), have a flow valve that shuts off or restricts the coolant flow when the heater is turned off, so unless you turn the heater on the condenser coil will not see any flow.
It should be a functional cooler for oil, though its placement is certainly less than ideal. But unless used with a thermostat that positively diverts flow through it (as opposed to just opening up a parallel path), it will most likely see little flow. And if used with flow diverting thermostat it may create a significant pressure drop in the supply to the engine, at the very least the pressure after the cooler should be checked (the stock sender is in the main gallery off the pump).
As for removing the coolant thermostat, the only thing to be gained by removing it from a properly functioning system is a slight increase in flow rate, if this shows a significant change in temp under normal running conditions there are most likely other issues that need to be addressed. And the disadvantages of running without a thermostat are real, yes in a specific situation a thermostat may not be necessary, but in general thermostats are a very good thing.
On the trans cooler, I’m not sure what the working pressure is, but some testing on a auto car with an inline pressure gauge should show if its in the right range.
XSNRG, any restriction in the low pressure drain side of the turbo’s oil system is a VERY BAD idea, it will inhibit oil flow through the turbo and most likely overheat the turbo shaft bearings. (edit-Skip covered this)
Gary