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I know someone who recently bought a sportwagen with the urea system. They said it was a $300 service once a year to refill the tank. Though you are probably ri

I know someone who recently bought a sportwagen with the urea system. They said it was a $300 service once a year to refill the tank. Though you are probably right that it can be done much cheaper yourself.

jessaustin 11y ago
It's an ISO-specified solution of CO(NH2)2 and deionized water. If evil automakers want to screw the consumer they could make the fill port difficult to access, but other than that it seems straightforward. The "once a year" thing is also strange, since DEF usage is totally dependent on miles driven and how "hard" those miles were. (High-RPM, high-turbo-pressure driving uses more than low-RPM, low-turbo-pressure driving.)
- chiph 11y ago
  Mercedes did this on the GLK - the fill port requires a special nozzle. So you buy one of their refill bottles, cut the bottom off, and use it as a funnel with your DEF of choice (since it's a standard ISO solution).
  - jessaustin 11y ago
    Fun fact: the fill nozzle at the truck stop is also standardized by ISO, so that it will fit all ISO-compliant "commercial vehicles and buses... having a gross vehicle mass of more than 3,5 t". I wonder how how much lobbying it took to convince ISO not to specify anything for smaller vehicles?
    - chiph 11y ago
      Some of the truck stops have DEF nozzles that require a magnet to operate, so the truck drivers don't put it into their diesel tank. There are adapters you can buy that will allow you to fill up your diesel-powered car or RV using the cheaper bulk pump.
ssmoot 11y ago
That's crazy. I think I probably paid $20 for DEF to cover the ~11,000 miles I drove in my truck last year (and I'd have to imagine it's thirstier than an economy car). You pop a blue cap under the hood, dump in the DEF, and you're done. RAM and Ford (starting this year I think?) make it even easier by putting the fill behind the fuel door right next to the fuel cap. 5 gallons seems to last me about ~5,000 miles. DEF only became required in US light-trucks ("1-ton" and below) for the 2015 Model-Year I think. Anyways, the fluid itself is about the same price as gasoline. A $300 service is just plain gouging.

jessaustin 11y ago

It's an ISO-specified solution of CO(NH2)2 and deionized water. If evil automakers want to screw the consumer they could make the fill port difficult to access, but other than that it seems straightforward. The "once a year" thing is also strange, since DEF usage is totally dependent on miles driven and how "hard" those miles were. (High-RPM, high-turbo-pressure driving uses more than low-RPM, low-turbo-pressure driving.)

chiph 11y ago
Mercedes did this on the GLK - the fill port requires a special nozzle. So you buy one of their refill bottles, cut the bottom off, and use it as a funnel with your DEF of choice (since it's a standard ISO solution).
- jessaustin 11y ago
  Fun fact: the fill nozzle at the truck stop is also standardized by ISO, so that it will fit all ISO-compliant "commercial vehicles and buses... having a gross vehicle mass of more than 3,5 t". I wonder how how much lobbying it took to convince ISO not to specify anything for smaller vehicles?
  - chiph 11y ago
    Some of the truck stops have DEF nozzles that require a magnet to operate, so the truck drivers don't put it into their diesel tank. There are adapters you can buy that will allow you to fill up your diesel-powered car or RV using the cheaper bulk pump.

ssmoot 11y ago

That's crazy. I think I probably paid $20 for DEF to cover the ~11,000 miles I drove in my truck last year (and I'd have to imagine it's thirstier than an economy car). You pop a blue cap under the hood, dump in the DEF, and you're done. RAM and Ford (starting this year I think?) make it even easier by putting the fill behind the fuel door right next to the fuel cap. 5 gallons seems to last me about ~5,000 miles. DEF only became required in US light-trucks ("1-ton" and below) for the 2015 Model-Year I think. Anyways, the fluid itself is about the same price as gasoline. A $300 service is just plain gouging.