I finally caved and tried the fuel additive that old timer swore by

Been running a 5.9 Cummins in my service truck for about 4 years now. This guy Harold at the parts counter kept pushing this one additive called Diesel Kleen, said it would clean up my injectors. I told him it was snake oil for like 6 months straight. Finally bought a bottle last week when I noticed some stumble at idle, poured half in with a full tank of fuel. Drove 200 miles hauling a compressor yesterday and that stumble is completely gone. Anyone else had good luck with fuel additives or is this just a coincidence?

3 comments

3 Comments

ivanross29d ago

Yeah man that's how it goes with a lot of stuff I've noticed. My buddy swore by seafoam in his old gasser for years and I thought he was nuts but finally tried it on a lawnmower that wouldn't idle and it fixed it right up. It's like with any old school trick you hear about - you gotta get burned a few times before you realize the old guys actually knew what they were talking about. Diesel Kleen is pretty legit though, I've used it in my old Ford for years and it keeps the injectors happy. The stumble coming back after treatment is a good sign it was carbon or some gunk buildup that got washed out. Probably a coincidence you got results right away but that's usually how it works when you actually need it. I bet if you kept running it you'd see even more improvement over the next few tanks.

felix_black29d ago

Hold up, let's not act like a little bottle of fuel treatment is gonna turn a junk engine into a daily driver. You put that stuff in and your truck ran slightly less rough for a tank or two? That's not a miracle, that's just burning through some thin buildup. Half the time people swear by this stuff it's placebo or they just want to feel like they did something. I've seen guys dump a whole can of Seafoam in a car that was burning oil and it just made a mess. You're better off just driving the thing hard for a week and see if that shakes the gunk loose on its own.

blair_martin29d ago

Hang on, you're telling me that old guy Harold actually knew what he was talking about? I've been ignoring that same advice for years from a mechanic I trust and now I'm wondering how much money I've wasted on injector cleaner that didn't do a thing.