Just wondered whether a person might "top off" the DEF tank instead of waiting for the warning stuff to light up and mess with my comfort level? Does it hurt anything to do this?
Well, take it from me, it really looks bad (from the first time I tried to fill the DEF tank in the dark), and I understand there is an ammonia factor in this fluid. That might be where the corrosion comes from. Fortunately, I did it this time in the garage, fully lighted, and standing on a little stool so I could reach inside the engine compartment instead of standing on my tippy-toes and hoping I get it right.