[brc]

All 'air cooled' engines are 'oil cooled' technically, including the Beetle.

The 911 has two oil coolers (well, from the mid '70s, anyway) - one in the right front fender, and one mounted to the engine itself.

[sandworm101]

Except for those engines that don't use oil. (Think toy airplanes.) And oil coolers are also found in some water-cooled engines. My old bike (2000 Honda VFR800) used both water and oil-filled radiators.

[brc]

Toy airplanes do use oil, it's just mixed in with the fuel.

Many water-cooled cars do have an oil cooler, but it's not the primary means of cooling the engine. In those cases it's more about keeping the oil at a constant temperature.

Oil cooled cars have sump capacities 2x water cooled cars.