I know that the town car uses 87 but people say That It will keep the engine clean if you use the 93. I have been putting 93 since I bought the car new from the dealership. I just read an article that says that if you use 93 in town car, carbon builds up in your engine. so what gas do I use in my town car now. Why did the 1998-2000 use 91 gas. I have a 2002 town car.