Thanks all for the responses; so glad I found the ACAA forum! The owner's manual for my 29 Dodge (The model is "DA six") provides that the "water pump bushing oiler" should be lubricated with engine oil every 2000 miles. It goes on to state that besides protecting the surface of the bushings, the oil prevents coolant from leaking out of the oil holes. I'm not sure I'm interpreting that correctly, but I think it means that if the oil bushing reservoir is properly filled with oil, coolant should not leak out of the oil fitting. Anyway, I removed the fitting, filled the reservoir with about a half teaspoon of oil (that's all it would take), and replaced the fitting. The fitting is not threaded; it's just a push-in plug (which I find odd, and I guess means the fitting is not subject to the normal pressure of the cooling system). So far it's not leaking but I haven't run the engine yet. It was previously leaking with the engine running or not running. I've attached two photos of the fitting in place. Thanks!