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What does diesel exhaust fluid do?
It is injected into the exhaust pipeline and reduces the amount of pollution, specifically nitrogen oxide, that is emitted from the engine.
Do you need to use diesel exhaust fluid? Can diesel engines run without it?
You can run older diesel engines without exhaust fluid, but it’s needed for modern engines as they will not start or run without DEF fluid.
How much DEF do I need to buy for my vehicle, and how often should I check and add more DEF?
You'll want to check your owner's manual to find out how much DEF you'll need, most tanks hold between 15 and 50 gallons. Your owner's manual should also indicate how long you can expect a fresh tank of DEF to last. A good rule of thumb is to top up your DEF tank once every 3-4 times you fill up the fuel tank.
