I didn't respond because I don't know if you are talking about Howes Diesel Treat, which is the anti-gel, moisture and lubricity product, or Howes Meaner Cleaner, which is the fuel system and injector cleaner.
For the diesel Treat, one ounce per 5 gallons of fuel in every tank. In the winter, twice that, 2 ounces of Diesel Treat for every 5 gallons of fuel. It needs to be used in every tank. The cost per ounce, at $15 a bottle, is $0.23. So, the cost per gallon is a little less than 5 cents in the summer, a dime in the winter. That's pretty cheap for moisture control, increased MPG, increased fuel filter life, and clean and lubricated injectors.
Howes Meaner Power Cleaner should be used at a rate of one ounce for every 10 gallons (a 32 ounce bottle treats 330 gallons). It costs about $0.47 cents an ounce, so it costs a little less than 5 cents per gallon, as well.
Meaner Cleaner in every tank will give you a 5% increase in MPG, which more than offsets the cost. I use Meaner Cleaner in every tank. Keeps those injectors clean.
Like Howes, Power Service also has two separate products, one that is more for anti-gel and the other that is more for injector cleaning. Howes Power Cleaner is arguably the best on the market for keeping injectors clean (too many studies have shown it to come out on top), so that's what I use for injector cleaning.
The two Power Service products are Diesel Fuel Supplement, and Diesel Kleen. Both are a "+Cetane". One is more +Ceane than the other, tho.
With winter being all gloomy and gray, you'd think that the Power Service anti-gel, the winter treatment, would be in a gray bottle. But noooo. It's in a pristine and pure white bottle, and the summer treatment, the one that does all the cleaning, is in the gray bottle.
The Diesel Fuel Supplement is anti-gel and does moisture control, lubrication, and has some injector cleaning detergents. It add about 4 cetane numbers to the fuel.
The Diesel Kleen has a much more concentrated cleaning package, the same amount of moisture control and lubricity, but adds about 6 cetane numbers to the fuel.
Most European, Canadian and all California CARB diesel is 50 cetane. Most American diesel is in the 44-45 range, with Flying J usually closer to the 41-43 range. A higher cetane number means a lower ignition point, meaning the fuel will ignite sooner in the combustion chamber, and will thus have a cleaner, more complete burn with fewer stuff left over to create carbon deposits. So raising the level of cetane means the injectors, among other things, will stay cleaner, and will be easier to keep clean wth injector cleaners.
My Sprinter has a European engine. (Well, OK, everyone else's Sprinter has a European engine, too.) But, it was designed with 50 cetane Euro diesel in mind. There is a phenomona known as Black Death, or injector seal blowback, that while still pretty rare here in America, is almost unheard of in Europe. It's where tar starts creeping up through the injector seals onto the top of the engine head, except that it's not gooey like tar, it's hard as diamonds, and will eventually crack heads and injectors. Because a lower cetane yields a dirtier, less complete burn, and the fact that Black Death occurs primarily in regions of low cetane diesel fuel, it's logical to make the connection between cetane and injector seal blowback.
The problems a Sprinter may have as a result of low cetane isn't likely to manifest itself so severely, if at all, in a big truck that is designed for a lower cetane, but you can bet a lower cetane leaves behind more deposits that have to be cleaned out and will result in less injector life.
Took me a while to get it all worked out, but that's why I now use the best injector cleaner (Howes Meaner Cleaner) and the best cetane boost (Power Service Diesel Kleen), which also has injector cleaners. Diesel Kleen costs more at one ounce for every 3-4 gallons, but it adds about 8% MPG and adds that cetane which gives a more complete burn thereby reducing piston and combustion chamber deposits.
So, for every 20 gallons of fuel, I add 5 ounces of Power Service Diesel Kleen, and because the Diesel Kleen has some injector cleaners in it already, I use one ounce of Howes Power Cleaner instead of the normal 2 ounce dose. That gives me superior injector cleaning, moisture (and algae) control, lubricity, and the cetane level that will reduce deposits and exhaust particulates.
In the winter I still use Howes Power Cleaner, and I use the Power Service white bottle Diesel Supplement. And if it's going to be below zero, I'll also add in half a dose of Hower Diesel Treat on top of that.
