Losing oil out breather

[GAHorn]

That article is much more informative than the service bulletin which I have not found. (The SB was only applicable to the O-200 engine as well, so.... if anyone wants to try this, they should understand they'll need to confirm there's no interference with rotating parts in the O-300, and...they'll need to find a basis of approval.)

From another post:

It should be noted that the routing of the crankcase-breather lines are different for the O-200 vs the O-300 engines. The O-200 (to which the extended elbow applies) exits the crankcase and immediately turns downward, which encourages any oil within the tube to exit the engine.

The O-300 on the other hand, turns aft and first runs horizontally... and the tube has a slight rise in it (notice where item 55 is pointed) on it's way to the rear cooling baffle, before it turns downward. This different routing encourages oil to remain in the engine. So it's doubtful the extended elbow would be necessary in a C145/O300 and may explain why TCM does not provide for installation in that engine.

From B-model IPC pg 70