Hi, Matt,

Change the oil, clean it up and drive it some.

Best,

Depending on the oil pressure pipework it could be a weep at the join between the hard line and the rubber flexi-pipe.

Check the tappet chest covers too, they can leak and the oil will dribble down in the manner described.

Well that makes sense.  There could just be some residual grease from when the cv joint spewed about 5 years ago.  It doesn't seem like motor oil but grease.  

The oil pressure sending unit should be on the front side of the engine and nowhere near the differential.

It is a testament to my late Father's ability to deal with annoyances.  And his sheer skill at dialing in an SU carb.

The damn thing started right up today after hibernation from the winter.

1.)  Definately need to replace the LF wheel cylinder.  Should solve the low brake fluid in the reservoir.  Thank goodness those rims are powder coated.

2.)  The lower coolant hose is showing some signs of deterioration.  There is a crack lengthwise just before the clamp on the "lump" end.  Preventative and probably because the car sits so much.  

3.)  I think there is some sort of leak at where the oil pressure sending unit goes.  It is not substantial but the bottom of the block and on the top of the differential.

4.)  ⇑  On that note the engine bay along with the entire car needs a really good detailing.

In conclusion, I am pretty sure all of that isn't rocket surgery.  Hope to see all your pics from Mini 59...