Oiling the grill helps to keep the fish from sticking. But it's not a perfect solution. The trick is to minimize the sticking. Try strewing the oiled rack with thinly sliced assorted citrus fruits or whole green onions. Instead, make a few slashes, cutting at an angle about an inch or so deep, along the midsection of both sides of the salmon.
Stuff slits with aromatics, such as thinly sliced citrus or sprigs of herbs.
Trim the tail, if necessary, or wrap it in foil. Grill salmon, covered, over indirect heat until it is cooked through and flakes easily. Set aside for 5-10 minutes before slicing. Sear, skin-side down if applicable, over direct heat for 3 to 4 minutes. Transfer the fish to indirect heat and cook until the salmon is cooked through and flakes easily.