If you mean oil-based attractants, the strongest matches are the Pro-Cure bait oils. Pro-Cure, Inc FRESHWATER SHRIMP BAIT OIL and Pro-Cure, Inc SAND SHRIMP (GHOST SHRIMP) BAIT OIL are built to add scent to bait or lures, especially for trout, salmon-steelhead, panfish, and kokanee. Pro-Cure, Inc SHRIMP / KRILL OIL is another versatile scent option for corn, eggs, yarn, flies, and natural baits.
For carp-style oil use, Baitworks MONSTER RED SUPER SPICE OIL is a thin, PVA-friendly oil for bottom baits, stick mixes, and surface baits. Parker Baits Flat Spot – Fruity is also an oil-based attraction option aimed at visual surface “flat spot” signaling.
Switch away from oil-based attractants if fish are reacting more to movement, profile, or depth control than scent. In that case, a lure or soft plastic presentation is usually better than an oil. Also switch if you need a specific forage match beyond shrimp/krill/spice, or if the water is so turbulent that scent disperses too quickly.