"Flyboys" Gotha Question

[Epee]

In the movie "Flyboys" the Gotha scene opens with a crewman on the wing catching water from the radiator in a mug or stein. Why? I know the engines sometimes needed service in flight but what purpose would catching the water serve? Making coffee?

[Buzzard]

I could be in error, but I thought he was oiling the engine

[Ransom E. Olds]

Haven't seen the movie, but did see the 6-minute combat clip. I thought the fellow was using the coolant as hot water to make tea--more of a jeu d'esprit than anything else, given the circumstances. Ransom