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Some companies have been adding additives lately. They can somehow interfere with the system and lead to a DEF Quality Poorq warning. I don't know why it happens.
Def is 32.5% ammonia and the rest is distilled water. There better not be any thing else in there. Any more ammonia and you will get what is called ammonia slip past the scr and the rear nox will see it as a rise in outlet nox. Any less and the scr won’t convert
 

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I bought a case of DEF additive from europe. Xenum Admax.


I bought a case of it (shipped from europe) as my daughter plugged the scr cat in our 2017 cruze diesel - short trips while she had the car at college. The cat was replaced under warranty.

The benefits of this additive are on the page above. I recall it is a fatty acid that keeps def injector and scr cat clean. Stabilizes the DEF. And reduces the temperature it crystalizes for cold weather operation.

I would imagine that any "premium def" might use something similar and have the same benefits as admax....

jeff

p.s. we sold our diesel cruze to carmax a while back - I have a case of the admax and a case of nex10; AdMax keeps DEF/SCR cat clean and happy. The nex10 is a DPF cleaner and reduces soot for cleaner DPF & EGR... If anyone is interested, I will pass them along to you at my cost, or maybe less (I want to get it out of my garage...) Just drop me a private message.
Adding anything to your DEF system is asking for trouble. I have been working Kenworth for the past 13 years and I deal with the aftertreatment systems daily. That is nothing more than “snake oil” and false claims. The scr does not affect fuel consumption. The the DPF in a regen does as the engine “in our case the #4 injector on the exhaust stroke” doses diesel fuel to react with the DOC to bring the DPF temps to between 977 and 1077 in a controlled manner to convert soot to ash and safely pass the dpf and into the atmosphere.
 

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I have been using Blue Def Premium. My fuel mpg increased and I have fewer sensor code alerts.
Def is injected after the engine and into the exhaust. Hints diesel exhaust fluid. It will in no fashion affect fuel economy. What will affect fuel economy is and not limited to. Fuel quality, your foot, air temp, engine temp, stop and go vs highway driving, If your in a regen.. that’s a big one… how loaded you have the car, dirty air filter, oil weight, tire pressure but def does not help propel the vehicle in any fashion so it can not help or hurt mpg. Plus. The tank last right at 10k miles. Who here keeps up with a 10k avg mpg? And rests every full up and tries something different? Please don’t spread bad info. Check ISO 22241 and you will learn about def and how it works


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Indirectly I believe it may actually or more correctly stated, nox2 directly measures nox levels and allows for a more precise urea dosing control based on the conversion efficiency of the catalyst and this allows the engine to run leaner and achieve better fuel economy.

Def Platinum, who knows. But the scr system is designed to always maximize the conversion factor to meet emissions and burning less fuel ie: better mileage, is a part of it.
There is no fuel trim feedback from the nox sensors. The closest your gonna get is if it seeing the egr is needed more to meet emissions and that harms economy. But still. Def fluid is not going to help economy . That’s in your driving habits and the driving conditions at that given time. Def is 100% an after thought to fix the problem. If you have a scanner you can watch the nox drop with egr. Egr works great at lowering combustion temps to lower nox but it’s not perfect by any means. We all know egr downside. def is there only to scrub what the egr couldn’t prevent in the first place. Now it does work the other way around. You are heavy footed and the def system is working harder to keep nox to a min and you will consume more def. But buying a “premium” def will do you no better than that off brand so long as it meets the iso 22241. Here is some more info



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Read the advertisement again.

It doesn't say that it will increase fuel economy.

It states that it will prevent a decrease in fuel economy. There is a difference.

This is done by keeping the scr cat cleaner and not becoming clogged.

This can happen on short trips where the scr cat doesn't get up to a good temp. Thr Def will crystallize and clog thr scr cat.

Note that this is much more likely happen in a Diesel passenger car vs a big rig kenworth. It happened to my Diesel cruze...

Jeff
Now that makes more sense. I was not going to argue any more about it. Yes. That is not an issue on Class 8 but they do over dose for one reason or another. I did have a hung open doser and it filled a Decomposition pipe lol. What a mess…. Def is water soluble and if crafty, you can remove the scr and simply was it out. I don’t have that issue with mine bc I drive 55 miles one way to work and it’s all 65+ for 50 of it.

P.s. thanks for clarifying my miss understanding.


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