Preheat outdoor grill to a medium temperature.
Shuck fresh corn, rinse and pat dry. Lightly brush each with vegetable oil.
Whisk together sour cream, mayonnaise, cotija cheese, cilantro and lime juice in a small mixing bowl. Add salt and pepper to taste. Refrigerate to chill.
Grill corn until slightly charred, or to your desired level cooking. Remove from grill and let cool for just a few minutes, then liberally spread on cream mixture, sprinkle with chili powder or Old Bay seasoning and a squeeze of lime juice to garnish. Serve immediately!