Ditched

It'll really want a decent run to get some heat into the exhaust if that's the case to burn the oil out.

I'm glad you're both OK.

It's always best to leave engines that have run upside down to settle. If you try too early and oil is above the pistons then you can get a hydraulic lock and bend something.

I'd say this was just oil that had seeped past the rings , like EMB said.

My experience was before the new inspection rules came in.

Now I think first you need to establish it hasn't been classes as an A or B write off, these cannot be put back on the road.

After suitable repair:

C needs a full vehicle identity inspection

C or D need an engineers report and an MOT before they can be reinsured (at least with the NFU)

AJH