Can a decent soft hackle be made using mallard flank feathers? If so, does it matter if there's still some of the natural oils in the fibers?

I have a bag of mallard flank feathers from a local hunter and they're pretty clean, except for the natural oil. Anyway, I need to start using some of the materials I've gathered over the past couple of years and thought of soft hackles for an outing on Saturday. I don't have any other likely candidates for soft hackles that display the peppered appearance the mallard does.

Thanks for any ideas and info.