It might not have been previously cross threaded. On mine a piece of the Aluminum Nipple stuck in the threads of the Nut and proceeded to act as a cutter and cut up the last 3 threads on the Nipple when I removed the Oil Cooler Line nut.

The "Screwed Nipples" are actually the same fittings that screw into the Oil Filter housing + there is a Metal Seal Ring that goes between the Fitting and the Oil Filter Housing.

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84 300D, 82 Volvo 244Gl Diesel