Well the Spit losing oil and coolant makes sense. Like the P-51 and Me 109, it has the oil cooler and radiator hanging out in the open under the belly. In this position it is easily hit from the rear, bottom, sides, or front.
However the N1K2 has the oil cooler (correct me if I'm wrong) under the nose. It's not hanging out in the breeze like on the wimpy inline planes. Fw 190 and P-47D also have the oil cooler close to this position. Seems like it would be hard to hit the oil cooler unless you were firing from the front, or underneath.
However keep in mind that oil coolers are pretty fragile items. All it takes is one nick of the cooler or it's supply and return lines, and your engine's lifeblood is spraying into the wind...
[This message has been edited by funked (edited 08-11-2000).]