Which engine oil fits your car: 5W-30, ACEA and approvals explained

What does 5W-30 mean?

The number on the bottle is the viscosity: how thick or thin the oil is. Castrol explains it like this: the W stands for winter, the number before it tells you how well the oil flows at a cold start, and the number after it how thick the oil is at 100 °C, the temperature of a warm engine.

• The first number (0W, 5W, 10W): the lower it is, the more easily the oil flows through a cold engine. A 0W oil is thinner at a cold start than a 10W oil.
• The second number (20, 30, 40): the higher it is, the thicker the oil at operating temperature.

Thin oils with a low HTHS viscosity, such as ACEA class C5, are meant according to ACEA only for engines designed for them and approved by the car maker. Don't pick a different viscosity from the one in the manual yourself. The catalogue includes Liqui Moly Top Tec 6200 0W-20, Castrol Edge 5W-30 C3 and Liqui Moly Leichtlauf 10W-40.

ACEA: A/B and C

ACEA is the European association of car makers. It writes the European oil sequences: a letter and a number, followed by the year of the version (for example C3-23).

• A/B oils are for petrol and diesel engines, with more ash-forming additives (high SAPS, as ACEA puts it).
• C oils are, according to ACEA, compatible with catalytic converters and particulate filters (DPF and GPF), because they contain fewer ash-forming additives (low or mid SAPS). Which class your car needs is in its manual.

Within the C classes, the main difference is the minimum HTHS viscosity, the thickness at high temperature and high load. ACEA sets a minimum of 2.9 mPa·s for C2, 3.5 mPa·s for C3 and 2.6 mPa·s for C5. So C3 and C2 are not simply interchangeable. An oil such as Castrol Magnatec 5W-30 C3 names its class in the product name.

API: SQ, SP and earlier classes

API is the American counterpart. For petrol engines API has had SP since May 2020, and since 31 March 2025 the newer class SQ; oil maker Chevron calls SQ backward compatible with cars that use SP. API says an SP oil gives full protection where the manual calls for SN. API also advises following the owner's manual first. For a European car, also check the ACEA class and the car maker approval in the manual.

Your car maker's approval

Many car makers have their own standards on top of ACEA. You see them as codes on the bottle and in the product name, for example:

• VW 504 00 / 507 00 for Volkswagen;
• MB 229.51 for Mercedes-Benz;
• BMW Longlife-04 for BMW.

One example is Petronas Syntium 5000 AV 5W-30: its name lists ACEA C3, MB 229.51, BMW LL-04 and VW 504.00/507.00. Liqui Moly Top Tec 4210 0W-30 lists ACEA C3, BMW Longlife-04 and MB 229.51/229.52. Mannol Longlife 5W-30 lists 504/507. If the code from your manual is not on the bottle, choose another oil.

How many litres?

How much oil your engine takes is in the owner's manual too, often with and without a new oil filter. For topping up between services, a 1 litre bottle is usually enough, such as Castrol Edge 5W-30 C3 in 1 litre. For a full change, 4 or 5 litre bottles are common, such as Castrol Edge 5W-30 C3 in 4 litres. Packs of 20 litres and more are meant for workshops.

Top up with the same oil that is in the engine, or with one of the same viscosity, class and approval. Check the level with the dipstick on level ground, after the engine has been off for a while.

Compare prices

Under engine oil you find every oil with prices from several shops. Each bottle size has its own EAN and Sorppa compares them one by one, so a 5 litre bottle is never compared with a 4 litre one. Brands such as Castrol, Liqui Moly and TotalEnergies each have their own page.