Ok thanks for that. All ideas are helpful.

What I see, is that doing it that way still requires R&R of the complete line - which is said to be difficult. And there is still the risk of damage to the cooler threaded nozzle when removing.

Buying a complete OE type line would no doubt be equivalent and preferred. But only the top line seems to be available from MB, and I would need the lower one.
That brings me to my question above about the aftermarket lines on eBay made by Vollig.

Avoiding R&R of the complete line, would favor using Diesel911's method of leaving the metal lines in place at both ends and hose clamping a piece of good quality/size hose in place of the existing swaged hose. However, if the leak is at the cooler union connection, then that connection would still need to be removed (with risk of damage)

Alternatives In summary:
1. Replace line with a complete OE or OE equivalent line.
2. Remove line and have hydraulic shop replace hose and re-swage.
3. Cut off swages and remove old hose. Replace with double clamped new hose.

First thing for me, is to thoroughly clean from end of hose to cooler, then watch to see where leak actually is.

If at union, buy a nozzle repair fitting from dealer before attempting to loosen the union. Tap should be available at short notice locally. Another thought, is to cut union nut off existing line and just use the cooler end of an aftermarket hose.

Question - How much of engine oil needs to be drained before disconnecting lower cooler line?

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5