Thread shrimp and scallops alternately onto long skewers. Brush the seafood evenly with the vegetable oil. Sprinkle with salt and pepper. Reserve. Blend 1/2 c ketchup with 1/4 c orange juice, 1/4 c maple syrup, 1 tbsp worcestershire sauce, 1 tbsp apple cider vinegar, 1/2 tsp paprika and 3 cloves garlic minced. Preheat the grill to medium-high heat and grease lightly. Brush kebobs all over with the maple-orange mixture. Grill for 2 to 3 min per side, basting often, or until shellfish turns opaque.