So I've been trying out this fuel additive on my 2004 F350 6.0L Diesel, and I'm almost through the second tank. It does feel like it starts up a bit smoother now, and the injector issues seem somewhat better, though not totally gone. With 260K miles on it, I wasn't expecting magic. I'm planning to get a few more bottles and see how it goes. If it fixes the injector problem completely, that'd be awesome. If not, I guess it's a trip to the dealership for a pricey $5K injector replacement. Fingers crossed it works!