"I've got a 2004 Nissan Titan that I bought new. It has had a a couple of noisy fuel injectors for 9 or the 10 years that I've owned the truck. I've run several of the other well known brands of fuel system cleaners through it over the years with some degree of success in terms of how well the engine ran, etc., but the injector noise never went away. I eventually just chalked it up to bad QC on the part of the manufacturer, but the truck ran fine, so I just accepted it. The truck is now a back up vehicle, so it doesn't get used much. I decided to get some fuel system cleaner and did a little research since I couldn't find my usual cleaner that I run. Lucas Oil Deep Clean was suggested as being one of the best on the market, so I bought some, dumped it in and drove around enough to get it through the entire system. I parked the truck for a couple days and then drove it again last night. What a difference. The truck started better, idled smoother, and as I drove it, I realized that the injector noise was gone! I'm hoping that it will also help increase gas mileage, but that will be harder to determine since the truck doesn't get used much. The difference? Based on my research, PEA (poly ether amine) is the best fuel system cleaner, carbon deposit remover, etc. out there, and Lucas Oil has it in their product. I don't believe testimonials when I read them; so it's understandable if you don't believe mine, but this stuff took care of an issue that I've been living with for 9 YEARS!" -Jason Bowker