Diesel Exhaust Fluid is used in many modern diesel-powered vehicles equipped with Selective Catalytic Reduction (SCR) systems to reduce harmful nitrogen oxide (NOx) emissions. Whether or not you should keep the DEF tank full depends on several considerations:
- Your Driving Habits: If you’re frequently on the road, especially for long distances, it’s a good idea to maintain a higher fluid level. If you run out of the fluid, your engine might not perform as well, or your vehicle could enter a “limp mode.”
- Avoid Contamination: DEF is a precise blend of urea and deionized water. By keeping your tank full or close to full, you reduce the risk of contaminants getting in when you top up. Ensure you always use clean equipment and DEF that complies with the right ISO standards.
- Prevent Crystal Formation: When a small amount of diesel exhaust fluid gets exposed to air, say if your tank is nearly empty, it can crystallize. Over time, these crystals can cause blockages. By keeping your tank reasonably full, you help prevent this issue.
- Cold Climates and DEF: The fluid will freeze at about 12°F (-11°C). If you live in an extremely cold area, having a fuller tank means a larger thermal mass that freezes more slowly. But don’t worry too much; most tanks in modern vehicles have heaters to thaw the fluid if it does freeze.
- Think About Storage: DEF has a shelf life — typically two years if stored in a cool, dry spot. If you know you won’t be using your vehicle much for a while, you might not want to fill the tank entirely. This ensures you aren’t storing the fluid in the tank for too long.
- Consider the Costs: You might prefer to keep your DEF tank full to sidestep future price hikes or to take advantage of discounts when buying in bulk.
In essence, while you don’t need to always keep your tank brimming, you shouldn’t let it run dangerously low either. Keep an eye on the level and top it off as necessary. Remember to always ensure the quality of the DEF you’re using and store any excess properly to maintain its effectiveness. If your vehicle warns you about low levels, make sure to refill soon to avoid any disruptions in performance.
Read related article: What Happens If DEF Gets Too Hot? (These 4 Things Occur)
The General Rule of Thumbs When Refill Your DEF Tank
When you drive a diesel vehicle equipped with a Selective Catalytic Reduction (SCR) system, you might have noticed that the Diesel Exhaust Fluid doesn’t deplete as fast as diesel. This is because the DEF consumption is generally designed to be a fraction of diesel fuel consumption. Following the guideline of filling your tank once for every 3 to 4 diesel refuels keeps things simple. You won’t have to constantly check the level, and by the time you’ve refueled your diesel tank 3 to 4 times, you’ll naturally know it’s time to top up the DEF.
This practice ensures that your vehicle remains compliant with emission standards and operates optimally. The SCR system in your vehicle requires diesel exhaust fluid to reduce harmful nitrogen oxide emissions. If you ever run out of DEF, you might face restrictions in your vehicle’s performance, or it might even enter a “limp mode” in certain cases.
Being consistent with this ratio also means you can be cost-effective with your purchases. Instead of buying in smaller quantities or waiting until a warning light reminds you, you can purchase in larger amounts or when there’s a sale, knowing your regular usage pattern.
Lastly, by maintaining this fill-up pattern, you help keep your SCR system in good health. Keeping a steady level prevents issues like crystallization or air getting into the system, both of which can lead to maintenance challenges. In essence, adhering to this ratio not only makes your life simpler but also ensures the longevity and efficiency of your vehicle’s SCR system.
Pros of Keeping the DEF Tank Full
Keeping your Diesel Exhaust Fluid tank full offers several advantages for your vehicle and your peace of mind. When you maintain a full DEF tank, you minimize the risk of contamination. The fluid is a sensitive blend of deionized water and urea, and each time you open the tank, there’s potential for external elements to sneak in. If contaminants get into your DEF, it can hinder the proper functioning of the SCR (Selective Catalytic Reduction) system, potentially leading to increased emissions and even engine damage.
Additionally, ensuring a full DEF tank helps prevent the fluid from crystallizing. If the fluid gets exposed to air or if the tank runs low for a while, it can start to form crystals. These can eventually block the lines feeding into the SCR system or damage its components. Keeping the tank topped off ensures the fluid stays consistent and prevents unwanted air exposure.
Lastly, for those spontaneous long drives or unexpected trips, having a full DEF tank is incredibly convenient. You won’t need to worry about frequent top-ups on the go. Depending on your driving conditions, such as highway versus city driving, consumption can vary. With a full tank, you’re better prepared for these changes in consumption. It means you don’t have to stress about finding a place to refill DEF or pay inflated prices at far-off stations.
So, by keeping that tank full, you’re not only safeguarding your vehicle’s performance but also ensuring a smoother, worry-free driving experience.
Considerations Against Keeping the DEF Tank Always Full
While maintaining a full Diesel Exhaust Fluid tank can offer several benefits, there are also some considerations to keep in mind that might advise against always keeping it topped off.
Firstly, you have to be aware of the shelf life and degradation of the fluid over time. Just like many other vehicle fluids, DEF doesn’t remain optimal indefinitely. It’s composed of deionized water and urea, and over extended periods, this mixture can degrade, especially when exposed to temperature extremes. If you’re always topping off your tank but not using the vehicle enough to consume it, you might find that the fluid loses its efficacy, potentially affecting the performance of the SCR (Selective Catalytic Reduction) system.
Then, there’s the concern of possible wastage, especially if you aren’t using your vehicle frequently. If you have a full tank of DEF but only drive sporadically, you might end up having to dispose of the fluid if it degrades before use. This not only results in wasted money but also adds an unnecessary task of draining and replacing the fluid.
Lastly, storage concerns arise if your vehicle remains stationary for prolonged periods. If you have plans to store your vehicle for an extended duration, continuously having a full DEF tank might not be ideal. Over time, the fluid can crystallize or settle, potentially leading to blockages or damage when you eventually start your vehicle up again.
While it’s essential to ensure your vehicle has enough DEF for its needs, it’s equally vital to consider these factors and understand that sometimes, there might be reasons not to keep the tank constantly full. Balancing the benefits and potential drawbacks can help you make an informed decision best suited to your vehicle’s specific circumstances and your driving habits.
To Make a Conclusion
Navigating the intricacies of diesel exhaust fluid can seem daunting, especially when you’re deciding how full to keep that tank. While you might think topping it off constantly is the way to go, it’s essential to understand that a more nuanced approach serves you best.
Your driving habits, the climate you live in, and the nature of DEF itself should guide your decisions. By keeping an eye on your DEF levels and adapting to your vehicle’s needs, you’ll strike the right balance, ensuring your vehicle performs efficiently, stays compliant with emission regulations, and enjoys a longer, healthier life. Remember, it’s not just about the quantity in the tank, but the quality of care you give to your vehicle’s SCR system.