How long DEF lasts depends on how many miles you get after filling the DEF tank, or if you buy it in bulk, how long your supply lasts. Store DEF in a cool, dry area, away from direct sunlight and ...

Best practice for DEF levels is to add or top of DEF tank every time diesel is added. The DEF fill cap is an industry standard blue and easily identifiable. Can it be stored anywhere? No. DEF will ...

DEF should never be mixed with diesel fuel, and it has its own filling port. But fuel and DEF tanks are close in proximity on some equipment, so it’s not surprising this mistake occurs.