I'd like some help identifying the roof on top of my garage, and how one
might lengthen its life.

It's flat, black, and .. "crispy". There are spots on the roof that, if you
touch/step on them, collapse like a flexible, crunchy bubble. It doesn't
feel rubbery, it feels "papery".

Am I correct in thinking this is a tar-paper roof? -- Can't say I see any
"tar brush strokes", so as a non-roofer, I am not sure what it is.

More Importantly: If it is a tar paper roof .. is there a product, perhaps
liquid, that one can spread on the roof to make it last longer?

At the moment, there are no leaks that I know of, but because it's flat,
there's often standing water up there and someday, it'll fail.

Thanks in advance!