A lot of current (and even slightly older) Mazda and Ford passenger cars use an oil/coolant heat exchanger which both cools the oil when it's up to temp as well as heating it up faster when it isn't. Attached is what the basic assembly looks like (black part is the exchanger, green is the oil pressure sensor) as well as a quick and dirty cooling system map for my car (2009 Mazdaspeed 3).
The cooling system map may not make much sense but the basic gist of it is that the coolant comes out of the head, goes into the heater core (which has its own internal bypass), comes back out and goes into the oil cooler, which then dumps back into the thermostat housing where the flow cycle starts all over again. These cars use a constant mix of radiator coolant as well as engine block coolant but never draw 100% from the radiator (which is pretty small as it is).
Hope this helps you find more options.
