Went for about a 20 mile ride to get blue berries this afternoon. When I got back into town I parked for a few minutes to go to a store, when I came back there was a small pool of oil under the front of the car. The copper outside oiler line had snapped off at the front fitting. Fortunately the oil level was still above the lower petcock so no apparent harm. Replacing that copper line with a steel one was on my list of things to do, now its at the top of the list.
I know many T's have out side oilers and most of those have copper lines. I think I'm pretty aware of what's happening with my T's, its my opinion that the line went from no apparent leak to broken off in that 20 miles.
If you have an out side oiler with a copper line replace it now rather than later, I was fortunate!!!