According to the owner’s manual, a full DEF tank should last 6300 miles, but, as everyone knows by now, your mileage will vary. That reservoir’s fill cap is under the hood atop the left fender. Our Range Rover is equipped with a 3.0-liter turbo-diesel V-6 that sips DEF from a 4.8-gallon tank located under the floor beneath the driver’s seat. Here, we’ll focus on the 2016 Land Rover Range Rover HSE Td6 we’ve enjoyed driving more than 30,000 miles since last spring, but we’re also keeping watch over a 2016 Nissan Titan XD powered by a 5.0-liter Cummins V-8.
The two long-term diesel-powered vehicles currently in the Car and Driver test fleet are proving useful for studying DEF consumption scenarios. To avoid the problem of owners stranded at the side of the road, every diesel-vehicle maker provides ample warning before it’s time to add DEF. The Environmental Protection Agency requires makers of new light-duty diesels to interrupt the engine’s normal startup routine if the DEF runs out to make sure owners take their clean-air responsibilities seriously. The ingredients remain in solution, so no shaking or mixing is necessary before use. While DEF doesn’t deteriorate over time, it can freeze, so store your supply in a heated location.
Make sure that any DEF you purchase is labeled to comply with ISO (International Organization for Standardization) 22241 specifications.
This produces three benign tailpipe gases: nitrogen, water vapor, and carbon dioxide. Those two compounds then react with oxygen and detrimental nitrogen oxides inside the vehicle’s selective catalytic reduction (SCR) catalyst. Inside the exhaust pipe, the DEF vaporizes and decomposes into ammonia and carbon dioxide. It’s contained in a reservoir separate from the fuel tank and is metered into the engine’s exhaust stream to control certain emissions. Those who turn a DEF ear face harsh penalties.ĭEF, available at most service stations for $6 to $10 per gallon, is a fluid consisting of urea and deionized water in a 1:2 solution.
DEF, also known as AdBlue or Blue DEF, is an elixir that’s necessary to make sure that what exits a diesel vehicle’s tailpipe is as sweet as an Alpine breeze. The following primer is for diesel-engine newbies and gasoline-engine devotees curious about life on the other side.
What happens if you run the treatment tank dry? We tested to find out, so you won’t have to try it yourself.ĭiesel veterans long ago learned how to handle this concern. As if it weren’t tough enough for diesel owners to find a clean place to pump fuel, they face another challenge: keeping their tanks of diesel exhaust fluid (DEF) topped off.