Have you figured out what the oozing is? I have a 'Somerset' maple that's struggled with aphids and borers. I just learned that, so this year was the 1st treatment. However, in the last month it looks like slugs have been climbing the tree. Slime all over its bark!

My guess is the photos are of an old would the tree has encapsulated. However since we don't know how to help trees seal off open wounds/wood it began to rot. Now when either sap flow is high or moisture gets in gunk comes out. Look up slime flux or bacterial wet wood on the google.