Preheat the oven to 400 degrees. Lay the corn ears on the top rack of the oven and roast for 30 minutes. When cool enough to handle, cut the kernels off the cobs and reserve.
Heat a large pot over medium heat. Add the corn oil. When hot, add the bacon and cook until rendered and beginning to crisp. Add the onion, leek and garlic. Cook until they have wilted, about 5 minutes.
Stir in the flour and then the half-and half cream, milk, clam juice and wine. Bring to a boil, whisk in the grits to thicken. Taste for seasoning. Add the corn and cook for 3 minutes. Add the mussels and cook for another 5 minutes until open, adding the calamari for the last 2 minutes of cooking.