VW and Porsche engines area really oil cooled. They have oil cooling radiators inside fan shrouds with thermal expansion baffles that open when it gets hot and close to prevent overcooling in winter.

They didn’t really overheat very often of all the shroud and engine compartment seals were in place and the baffles were in good working order.

The reason you can often go start up an ancient air cooled engine is mainly that they don’t have any water pumps (and water) to sit in them and rust up. That any that there’s no crazy fuel injectors or fancy electrical systems to fail. Just a Carb and distributor to clean/adjust.