1.Preheat a grill to medium heat. Brush the oil over the corn cobs.
2.Grill the corn for 8-10 minutes, turning occasionally until cooked through.
3.While the corn is cooking, whisk together the mayonnaise, crema, and lime juice in a small bowl.
4.Let the corn cool for 5 minutes. Brush the mayonnaise mixture all over the corn.
5.Sprinkle the cotija cheese, chili powder, and cilantro leaves over the corn, then serve.