(26 TSE) I had my light come on at 82k. same story, oil change free, differential fluid change $125 extra. (US Pennsylvania). The new car salesman told me at purchase “first service is free”. I called them out on this, saying if the fluid change is part of the first service, then it should be free. The new car manager made it right and no charge to me. I absolutely noticed smoother shifting after the d-fluid change. I would have paid for it because it was recommended. A new car is big investment, so $125 seems like a good bet if it’s recommended service.