Discover the 2025 guide to truly understand ACEA and API engine oil specifications. Avoid mistakes, respect your engine, and choose the right lubricant with clear advice.
When you need to choose the right engine oil, it's not enough to just look at the viscosity (like 5W30 or 0W20) .
ACEA and API specifications are key to ensuring compatibility, protection and performance .
Many drivers ignore these codes, but they are essential to avoid mistakes and to respect the manufacturer's instructions .
In this 2025 practical guide, you'll discover what ACEA and API really mean, how to read them, and why they're essential for your car's engine.
Castrol Magnatec 10W-40 A3/B4 Engine Oil - 4 Liters - Petrol and Diesel Engine Oil
Protect your engine with Magnatec technology: instant adhesion to metal parts for advanced protection right from start-up. Suitable for petrol and diesel engines.
✅ What is the ACEA specification?
ACEA is the European Automobile Manufacturers' Association.
It sets quality and performance standards for engine oils intended for the European market.
✅ Each ACEA specification indicates:
-
Level of protection against wear and deposits.
-
Resistance to oxidation.
-
Compatibility with post-treatment systems (FAP/DPF, catalytic converter).
✅ It is divided into classes and categories :
-
A/B → “standard” petrol and diesel cars.
-
C → compatible with FAP/DPF, low ash content (Low SAPS).
-
E → commercial and heavy vehicles.
🏷️ Practical example
➡️ ACEA C3 = “Low SAPS” oil, suitable for engines with DPF/FAP, guarantees compatibility with anti-pollution systems.
➡️ ACEA A5/B5 = low viscosity HTHS oil, for modern engines requiring fuel economy.
✅ What is the API specification?
API is the American Petroleum Institute.
Sets quality standards for engine oils globally .
✅ Each API acronym has two letters:
-
S = Service (petrol).
-
C = Commercial (diesel).
✅ The second letter indicates the evolutionary level:
-
The further along the alphabet, the newer the specification.
🏷️ Practical example
➡️ API SN → specific for latest generation petrol (high protection against deposits).
➡️ API CF → less advanced diesel (now superseded by API CK-4).
✅ Today, acronyms such as:
-
API CJ-4
-
API CK-4
✔️ They offer resistance to oxidation, compatibility with FAP/DPF.
⚙️ Why these specifications are essential
✅ Ensure compatibility with the engine.
✅ Avoid damage to FAP/DPF.
✅ Reduce wear and friction.
✅ Maximize efficiency and fuel savings.
✅ Maintain the manufacturer's warranty .
⚠️ Common mistakes to avoid
❌ Choose oil based on viscosity only (e.g. 5W30) ignoring ACEA/API.
❌ Use oils not compatible with FAP/DPF.
❌ Trusting generic or counterfeit products without clear specifications.
❌ Ignore the maintenance booklet.
💡 Practical tips for choosing well
⭐ Always consult the use and maintenance manual : the manufacturer indicates the specific requirement.
⭐ Check the ACEA and API acronyms on the product label.
⭐ Trust recognized brands (Castrol, Mobil, Shell, Total, Bardahl).
⭐ Avoid “too good to be true” offers → risk of counterfeiting.
⭐ If in doubt → ask a professional for advice.
🛠️ Why rely on a professional
A spare parts dealer or specialized workshop:
✅ Knows how to read and interpret ACEA and API.
✅ Check compatibility with modern engines.
✅ It prevents you from costly mistakes and damage to FAP/DPF systems.
✅ Offers only original oils or certified equivalents.
➡️ It's not an extra cost: it's an investment in the health of the engine.
🔗 Want to learn more?
👉 Also read our guide on 0W20 vs 5W30 oil to understand how to choose the right viscosity.
✅ Conclusion
The ACEA and API specifications are not useless acronyms, but the guarantee of choosing the right oil for your car.
✅ Get informed.
✅ Read the label.
✅ Follow the manufacturer's instructions.
✅ Trust those who can really advise you.
Because the right oil isn't an optional extra: it's the life of your engine. 🛢️🚗
