I was born in Portugal, and although I’ve spent time abroad, I know firsthand how different car ownership here can be—especially for those who’ve never driven a diesel. One thing I keep seeing is people moving here or buying a car locally, picking up a diesel because it seems like “the smart choice,” and then getting surprised when the car starts giving them trouble. Most of the time, it comes down to one thing: AdBlue—and driving patterns that just don’t suit diesel at all.

So, if you’re new to diesel engines or looking to buy a car here, let me help you avoid some common mistakes and explain what AdBlue actually is (and why it matters).

🚛 What Is AdBlue and Why Do Diesel Cars Need It?

AdBlue is a clear, odorless liquid made of urea and deionized water. It’s not a fuel additive—it has nothing to do with how the engine runs. Instead, it’s part of the emissions system in modern diesel vehicles.

🔧 The purpose of AdBlue:

It helps diesel cars comply with European emissions laws by neutralizing nitrogen oxides (NOx). When AdBlue is injected into the exhaust, it converts these harmful gases into harmless nitrogen and steam.

⚠️ What Happens If You Run Out of AdBlue?

Here’s the thing: without AdBlue, your diesel car will refuse to start. You’ll usually get plenty of warning—like a light on your dashboard—but if you ignore it, the car locks you out until you top it up.

🧊 The Big Mistake: Short Drives in a Diesel

One of the most common problems I see here in Portugal is people buying a diesel car and only driving 5 kilometers to work and back every day. That may seem harmless, but diesel engines—and especially their emissions systems—hate this.

Here’s why:

• Diesel engines take longer to warm up.

• Short trips never allow the engine or exhaust system to reach proper temperature.

• The DPF (Diesel Particulate Filter) doesn’t regenerate properly.

• You’re left with clogged filters, warning lights, and a trip to the mechanic.

I’ve seen friends regret buying diesel just months in. These cars are designed for longer journeys, not city center commuting or school runs.

⛽ How Often Do You Need to Refill AdBlue?

That depends on your mileage. A car that drives long distances may only need AdBlue every 8,000 to 15,000 km. But if you’re doing lots of short trips, the system may be less efficient, meaning more frequent top-ups.

Typical refill costs:

• €10–€20 if you do it yourself (10L jug from the gas station)

• €30–€70 if you let the dealership handle it

🤔 Should You Buy a Diesel in Portugal?

Let’s be real—diesel sounds good until you look at the big picture.

Diesel is great if:

• You drive 20,000+ km/year

• You travel long distances, especially on the highway

• You own a larger vehicle (SUV, van, 4×4)

Diesel is notfor you if:

• You mostly do short, daily drives (under 10 km)

• You live in a city or town with stop-and-go traffic

• You drive less than 15,000 km/year

💡 Personal Tip: My Diesel vs My Friend’s Petrol

I’ve owned diesel cars and love them for road trips and highway cruising. But my friend drives a petrol hatchback and does mostly local driving—and his maintenance costs are a fraction of mine.

Here’s a quick comparison:

🎯 Key Takeaways Before You Buy

If you’re about to invest in a car in Portugal, ask yourself:

1. How many kilometers will I drive per year?

2. Will most of my trips be short?

3. Am I ready for the extra care diesel requires (AdBlue, DPF)?

If your answer is “not much,” “yes,” and “no”—then buying a petrol or hybrid is the smarter move.

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🎧 Bonus: Listen to the Immo Lusitania Podcast

Hear from real buyers and locals about how to navigate Portugal like a pro—whether you’re buying, renovating, or figuring out life on the ground.

🎙️ Listen to our Spotify Podcast

🤝 Need Help Buying or Relocating in Portugal?

Immo Lusitania is your independent property expert in Portugal.

We help you find and evaluate properties, organize visits, and guide you step-by-step from negotiation to renovation.

📬 Reach out now via our contact form, or speak directly with our multilingual team:

• Ferdi Van Duijvenbode (English, Dutch, Portuguese): ferdi@immolusitania.ch

• Nadia (Swiss German, German): nadia@immolusitania.ch

• John (Finnish, Swedish): john@immolusitania.ch

  You can also schedule a call via Calendly or click the WhatsApp button to chat with Ferdi directly.

❓FAQ: AdBlue and Diesel in Portugal

What is AdBlue?

AdBlue is a urea-based fluid used in modern diesel engines to reduce harmful nitrogen oxide emissions.

How often does AdBlue need to be refilled?

Every 8,000–15,000 km on average, depending on your driving habits.

Is diesel good for short trips?

No. Diesel engines and their emissions systems require longer trips to function properly.

Can I buy a diesel if I drive under 10,000 km/year?

You can—but it’s not recommended. A petrol or hybrid car will be cheaper, cleaner, and lower-maintenance.

What happens if AdBlue runs out?

Your car will stop working until the tank is refilled.