I just give out all my secrets on this site
Speaking of oil and sponges, for fluking, I use the wide bend with the beads, blade, etc. Cut a piece of sponge (size depending on current), slide it down the leader near the beads, etc. I usually cut a longer about inch and a half, and small in width. Then I tie each end with line or rubberband to make it tapered, sort of looking like a small inline trolling sinker. Make sure you don't use one of those "cheap" sponges.....they don't hold water, and won't hold the oil either. Drip or dip in oil while "squishing" the sponge, fish as normal. The other advantage IMO, is it gives some Buoyancy and lets the bait ride a little higher, which I prefer.
I don't know if it attracts the flounder, or minnows that get the fish in a feeding mode (I think its the minnows), but it works...
