Put the chicken in a gallon-size zipper-top plastic bag. Add the oil to the bag, seal it and toss and turn the chicken pieces inside the bag until they are well-coated.
Mix the garlic powder, onion powder, cumin, oregano, black pepper and chipotle cubes in a small bowl, crushing the cubes with the back of a spoon. Add the spice mixture to the bag, seal it and toss and rub the chicken through the bag to coat well with the spices. Refrigerate the chicken in the bag for at least 4 hours and up to 24 hours. (Note: Prior to grilling, I still lightly season with salt the thighs.).
Heat a grill to about 400 degrees. Grill 5 to 6 minutes per side, until the chicken is cooked through, but still tender. Remove from the grill and serve. (The chicken may be cut into bite-size chunks for use in burritos or other recipes.).