DEF is easy to contaminate, and fortunately, it’s also easy to test. Check to be sure that your customers’ DEF is up to spec with these simple tests.

Break out your paint pen—you’re the service writer now!
Do you have a study guide to prepare for your ASE exams? Which parts of that study guide do you use the most? Dorman Training Center instructor Pete Meier explains.
Why wouldn’t your shop purchase a few of these?
Auto care news and advice you can use.
A Facebook reel that applies a psychological model to wrenching.
Reverse is an innovation that’s easy to take for granted—but it was a revolutionary addition to the automobile.
“Rebuild in a can” is not the right way to fix the tool, but it will get you by until you can repair it correctly.
Microtransactions spark unexpected microaggressions.
Working on a right-hand drive vehicle requires deviating slightly from a mechanic’s routine.
Shop Press is the news and idea hub for everything related to working on cars and trucks, focusing on repair, technology, and wrenching lifestyle. With interesting stories from around the world, features on creative people and solutions, and all kinds of other stuff that’ll make you use your mind and your hands.
Auto care news and advice you can use.
Putting up freight and pulling orders is more than busywork. It’s tuition.
Skillful interrogation is a wonderful way to make your professional life easier. Here are a few suggestions on where to start.
Think you know your dash lights? Shop Press contributors Keith, Miriam, Chris, and Greaser try their best to identify all kinds of lights, symbols, and indicators.
Don’t break fittings—break ‘em free.
That old smartphone can actually help when you don’t have a second set of eyes to help out.
A little glimpse into the world of making old parts new.
Inspection of a belt goes beyond the old standbys of checking for cracks and fraying.
On a car with disc brakes, what is the most likely symptom of a vehicle with rotors that measured out-of-spec for thickness variation when measured at several places on the rotor surface?