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Old 06-01-2020, 06:14 PM   #21
Dam Worker
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Tony my TV is a F-350 DRW with the 6.7 diesel. What I have read is the DEF usage drops on the Ford when towing/working the engine hard as it is doing a sort of regeneration because of the higher exhaust temperatures. Driving empty it regenerates more than when I tow especially if I am babying it. I try to drive it like I stole it a bit now driving solo and I have less regenerations. I can lose a little MPG driving it like I stole it or lose MPG when it does a 15-25 minute regeneration.
 
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Old 06-01-2020, 06:50 PM   #22
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Ford, GM, or RAM, DEF has nothing to do with Regens. Regens are related to the DPF, while DEF is sprayed directly into the exhaust stream in the SCR (Selective Catalytic Reduction).
The amount of DEF used is directly related to the amount of Fuel used. When working hard you're burning more fuel thus more DEF is used.
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Old 06-01-2020, 07:05 PM   #23
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What Michelle & Ann said.
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Old 06-02-2020, 02:47 PM   #24
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The tire of choice for Montana owners is the Sailun. Be happy, you got a great tire.
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DEF is not a fuel additive and never comes into contact with diesel. It is 32.5% urea and 67.5% de-ionized water regardless of the brand.. DEF is sprayed into the exhaust stream of diesel vehicles to break down dangerous NOx emissions into harmless nitrogen and water. DEF is not a fuel additive and never comes into contact with diesel. There is no effect on mileage regardless of the brand used.
DEF bought at a convenience store that is out of expiration, kept in the sunlight at high temps or freezing temps will definitely have an effect on the consumption rate of DEF as related to mileage. Purchasing mine at a GM parts counter ensures all these parameters were met thus better miles per gallon of DEF as per my experience. Diesel fuel mileage was not the issue.
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Old 06-02-2020, 04:03 PM   #25
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DEF bought at a convenience store that is out of expiration, kept in the sunlight at high temps or freezing temps will definitely have an effect on the consumption rate of DEF as related to mileage. Purchasing mine at a GM parts counter ensures all these parameters were met thus better miles per gallon of DEF as per my experience. Diesel fuel mileage was not the issue.
DEF that is old, kept in high temps or sunlight, or freezing temp has its effectiveness reduced significantly. The consumption is not affected. The SCR in modern light duty trucks introduces a fixed amount of DEF per unit of diesel fuel. Burn more more fuel (i.e. towing) and you consume more DEF. The SCR doesn't know or care about the quality of the DEF. Nor is there onboard NOX sensors to determine if the DEF rate is reducing the amount of NOX. The only way to test the effectiveness is via a Smog check (be sure to ask Volkswagen how they handle this situation).

Yes buying at the GM dealer should be a safe way to buy DEF. That is assuming it has been stored properly, not on pallets out back of the shop, and it isn't past its expiration.

Many of us buy the 2.5 gal. jugs at Walmart, O'Rielly's and such suppliers where they turn it over often. If you don't know how to decode the date/expiration code on the jugs here is one source
http://www.rvforum.net/SMF_forum/ind...?topic=73092.0

Others prefer the DEF pumps at truck stops where there is high volume and typically lower price.

The choice is yours to make. There may be times where a Chevy dealer is not available (ever been to Quartzsite?) and another source may be the only option.
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Old 06-02-2020, 10:17 PM   #26
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I stand corrected on my earlier statement of using less DEF under load. The more load on the engine the more DEF used but you have less regeneration’s because of passive regeneration when working the engine harder. DEF is cheap for the amount used but diesel can be expensive so I like when you have passive regeneration instead of forced regeneration.

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Old 06-07-2020, 02:38 PM   #27
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You're kidding us right, 75??
The speed limit is 80
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Old 06-07-2020, 03:06 PM   #28
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At sustained 70-75 mph you'll be the guy on the side of the road with at least one blown tire and a Monty with significant damage.
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Old 06-07-2020, 06:19 PM   #29
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Our 3500 uses 5 gallons of DEF in 2000 miles, almost exactly, when towing. I get an honest 10 MPG towing. Sometimes downhill or tailwind, it does better. A real feel good moment at the pump. I don't use the dash calculation, I calculate each tank manually.
I couldnt be happier with the mileage. My only gripe is that the truck does great on regens towing, passive regens are great. My gripe is as soon as i disconnect and go sight seeing it almost Immediately goes into regen. The dealer has looked at it numerous times and says all is okay. Around town regens are numerous.
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Old 06-07-2020, 06:20 PM   #30
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DEF is not a fuel additive and never comes into contact with diesel. It is 32.5% urea and 67.5% de-ionized water regardless of the brand.. DEF is sprayed into the exhaust stream of diesel vehicles to break down dangerous NOx emissions into harmless nitrogen and water. DEF is not a fuel additive and never comes into contact with diesel. There is no effect on mileage regardless of the brand used.
Actually I have known a couple of folks that have added DEF to their fuel tank. It is a $10K mistake.
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Old 06-07-2020, 06:32 PM   #31
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At sustained 70-75 mph you'll be the guy on the side of the road with at least one blown tire and a Monty with significant damage.
Dang..thanks for the kind words... FYI the tires are rated at that speed.
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Old 06-07-2020, 06:35 PM   #32
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Our 3500 uses 5 gallons of DEF in 2000 miles, almost exactly, when towing. I get an honest 10 MPG towing. Sometimes downhill or tailwind, it does better. A real feel good moment at the pump. I don't use the dash calculation, I calculate each tank manually.
I couldnt be happier with the mileage. My only gripe is that the truck does great on regens towing, passive regens are great. My gripe is as soon as i disconnect and go sight seeing it almost Immediately goes into regen. The dealer has looked at it numerous times and says all is okay. Around town regens are numerous.
Just flipped 2k in miles and I had to fill up the def tank. About 900 miles towing. Still in break in-period I guess lol
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Old 06-07-2020, 06:44 PM   #33
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Dang..thanks for the kind words... FYI the tires are rated at that speed.
I'll stop to help out.
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Old 06-07-2020, 06:45 PM   #34
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Dang..thanks for the kind words... FYI the tires are rated at that speed.

Mine are rated for 87.
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Old 06-07-2020, 06:49 PM   #35
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Mine are rated for 87.
Rated for posted speed limit +10 mph lmao
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Old 06-07-2020, 06:59 PM   #36
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Just a FYI...The DEF is used to reduce the NOx in the exhaust by use of a catalyst and the Fluid converting the NOx to water and nitrogen which goes out the exhaust.

Regeneration is the method of cleaning the DPF (diesel particulate filter) using injected diesel fuel to raise the temperature in the filter and burn off the soot.

Two different systems in the exhaust stream.
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Old 06-08-2020, 06:45 AM   #37
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[QUOTE=Carl n Susan;1185575] The SCR in modern light duty trucks introduces a fixed amount of DEF per unit of diesel fuel. Burn more more fuel (i.e. towing) and you consume more DEF. The SCR doesn't know or care about the quality of the DEF. Nor is there onboard NOX sensors to determine if the DEF rate is reducing the amount of NOX. The only way to test the effectiveness is via a Smog check (be sure to ask Volkswagen how they handle this situation).

Very useful info on this thread. I haven't done a detailed measurement but I seem to use about 3 times the DEF when towing as under local driving. Also when towing fuel consumption is increased by about 40%. Seems there is more that impacts DEF consumption.
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Old 06-08-2020, 07:43 AM   #38
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In my opinion the Sailuns are the number one tire to run, they are built to dot specifications and are a commercial tire rating.
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Old 06-08-2020, 07:48 AM   #39
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They are the best tire you could put on. They are commercial tires built to dot specifications.
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Old 06-08-2020, 08:06 AM   #40
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I get my DEF at truck stops for about 2.99/gal, and when I use my EFS card from TSD Logistics I get a little discount on the DEF as well as the fuel.
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