I have a -88 750 sport I purchased in boxes. Working on assembly, but I run into a little problem.
The bike has an optional mechanical oil temperatur instrument with a sensor. Not listed in the spare parts or workshop manual.
The diameter and threads is identical to the drain plug. But I find it unlikely that it should be mounted there instead of the drain plug.
I find no other obvious places to mount it. There is also a distance from the base to the threads. In one box I found a plastic ring that fits exactly as a spacer, but have no idea if this is just by coincidence or if they belong together.

Has anyone seen a sensor like that before and knows where and how it should be mounted, I would be very happy for some advice.

Hi TuTu...
I wouldn't have guessed Ducati put oil temperature sensors on the bikes, but it seems they do. I've seen the mount location on covers but never knew what they were for until now. I'd be more concerned about pressure than temp. and just delete that part.
Regards...
Flattop

You do not need it. Chuck it, and keep things simple. MikeV