If you "fill for life" that means your transmission will eventually DIE because you didn't change the fluid or the filter. These cars are known to drive for 300,000 miles with proper care, so if you stop maintenance at 80K miles, I would have to presume you want its life span to be shorter than 300,000 miles. It's up to you. As for me, if I still own the car in another 60K miles, I will change the fluid and filter again in MY car.