Man, your a good brother taking care of your sister's car like that. I do the same for my wife but that's just because she doesn't get what an oil change is. She had a 2007 Mustang that somehow she got to 2019 doing oil changes every 10k miles I'm guessing? I'm amazed the Stang lasted as long as it did with total neglect. I guess because it's their halo car they put stronger parts in it.