[sbierwagen]

  In 1969 on the 911S, a front mounted radiator-style cooler 
  was mounted as standard equipment in the front right fender 
  well. In 1973, the newer trombone, serpentine, loop or 
  cooling pipe cooler as it was called, replaced the radiator 
  style cooler. This style of oil cooler was used through 1983.

Ha! What the hell!? The 911 never actually was a purely air-cooled car, like the Beetle?

And now that I check wikipedia, I learn that the Beetle also had an oil cooler! My god, I've been living a lie.

[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.

[bradleyland]

Good thing you checked Wikipedia :) I was just about to point out that VW Beetle motors had a smallish oil cooler in (or near) the fan shroud at the front of the engine.