VIDEO: What You Need To Know About DEF


If you have a late model diesel powered motorhome, there’s a good chance it requires the usage of Diesel Exhaust Fluid, aka DEF. In this segment Robert Hitt of Prevost explains why DEF is needed and provides solid information on using DEF correctly.

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DEF is not something you want to let run dry. On my 2011 Ford 6.7L diesel, if I run the tank dry, the computer will eventually slow me to a maximum of 5 miles per hour. Check your owner’s manual to make sure you know how the system works. As well, I find buying in bulk at the truck stops, the cost of DEF is 1/2 the cost of buying it in the jugs.


I travel the Alaska Hwy where DEF is $25+ per jug. I’ll carry a couple with me, stored in a plastic container.


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