alright i got a 89 LX 5.0 with a stock motor. it had 157000 miles before the spedometer quit working (previous owner did it, probly close to 200k now) but it runs good no smoking or leaks or anything. i replaced all fluids and have seen alot of fuel injector cleaners that you add to gas tank. i however heard that these could mess up your engine, is this true? what does anybody know about them? if they are good what brand do you think is best?