Diesel exhaust fluid (DEF) is nothing new. GM’s Duramax-powered Chevrolet Silverado and GMC Sierra 2500HD and 3500HD pickups have had used the stuff since 2011. So has Ford’s F-Series Super Duty.

GM pickups powered by a Duramax diesel engine offer loads of benefits, including strong low-end torque and impressive real-world efficiency. However, diesel engines also require some specialized ...