ACEA C classes

Low-SAPS engine oil: the ACEA C classes C2 to C6 explained

Low-SAPS engine oil protects particulate filters and catalytic converters – but “low SAPS” is not a single standard. The ACEA classes C2 to C6 differ in ash content and HTHS viscosity. This page sets out the differences at a glance and shows which Elat oils list which C class.

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Engine oil being poured into the oil filler neck in a car’s engine bay

Engine oil, particulate filter, catalytic converter: why SAPS is limited

SAPS stands for sulphated ash, phosphorus and sulphur. Via the small amount of oil that burns in the engine, all three reach the exhaust system – and each has a different effect there:

Sulphated ash comes from metal-based additives such as detergents. It is incombustible, builds up in the diesel particulate filter and is not burnt off during regeneration.
Phosphorus comes mainly from anti-wear additives. It can deposit on the catalyst surface and permanently reduce its effectiveness.
Sulphur can impair catalytic converters, especially NOx storage catalysts.

Low-SAPS engine oil limits these components, which helps particulate filters and catalytic converters keep working for longer. Because such oils have to manage with fewer metal-based additives, they are specially formulated, and vehicle manufacturers put them through their own additional tests for their standards. Our motor oil guide gives a short introduction to oil types.

In brief

The ACEA C classes are designed for engines with particulate filters and catalytic converters. Strictly speaking, C4 is low SAPS, while C2, C3, C5 and C6 are mid SAPS; the classes also differ in HTHS viscosity. The owner’s manual tells you which class and manufacturer standard apply.

Last updated: 24 September 2026

ACEA C2, C3, C4, C5 and C6 at a glance

The ACEA C classes describe catalyst-compatible oils for petrol and diesel engines in cars and light vans fitted with particulate filters and three-way catalytic converters. They differ in two respects: the permitted levels of sulphated ash, phosphorus and sulphur, and the minimum HTHS viscosity, measured at 150 °C and a high shear rate.

Strictly speaking, only ACEA C4 is a low-SAPS class with a particularly low ash limit; C2, C3, C5 and C6 count as mid SAPS. In everyday usage – and on this page – all C classes are called “low SAPS” or “low-ash”. C4 allows a sulphated ash content of no more than 0.5 per cent by mass, the mid-SAPS classes no more than 0.8 per cent.

ACEA C classes: character, minimum HTHS and Elat oils listing the class on their label
ACEA class	Character	Minimum HTHS	Elat oils with this class
C2	Mid SAPS, lower HTHS viscosity for low-friction engines	2.9 mPa·s	5W30 Cipe C2, 0W30 Profi Tec for Euro 6, 5W30 Mega Tec LongLife 3 (C2/C3)
C3	Mid SAPS, high HTHS viscosity	3.5 mPa·s	5W30 LongLife 3, 5W30 Premium LongLife 3, 5W30 Extra LongLife 3, 5W30 Classic LongLife 3, 0W30 Zero Tec VW, 5W40 High Tec Quantum, 5W30 Mega Tec LongLife 3 (C2/C3), 5W30 C4 Ren Tec (C3/C4)
C4	Low SAPS, high HTHS viscosity	3.5 mPa·s	5W30 C4 Ren Tec (C3/C4)
C5	Mid SAPS, low HTHS viscosity	2.6 mPa·s	5W20 Ford Eco, 0W20 VW Tec Blue Oil (C5/C6)
C6	Mid SAPS, low HTHS viscosity, additional requirements including LSPI protection	2.6 mPa·s	0W20 VW Tec Blue Oil (C5/C6)

Elat engine oils with an ACEA C class

All twelve oils list an ACEA C class on their label, highlighted in blue on the cards. Further standards and the full details are on the product pages.

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Approval or specification?

Only expressly stated manufacturer approvals are marked “Approval”. All other entries are specifications and recommendations as printed on the product label; the entries relevant to this topic are highlighted. For your vehicle or machine, the owner’s manual and the manufacturer’s approval lists always take precedence. If in doubt, we are happy to advise you.

Choosing DPF engine oil: read the class and the manufacturer standard together

The ACEA class alone is rarely enough. Most vehicle manufacturers also specify their own standard, which builds on a C class and adds further engine tests. An oil with the right C class but without the required manufacturer standard is therefore not an equivalent substitute. This is how key standards map onto the C classes of Elat oils:

VW 504 00/507 00: every Elat oil listing these standards is specified to ACEA C3.
MB 229.52 and MB 229.51: Elat lists them on C3 oils, and in the case of C4 Ren Tec (MB 229.51) on an oil with C3/C4; Mercedes-Benz MB 229 engine oil has the details.
BMW Longlife-04: also on C3 oils, such as the LongLife 3 oils and High Tec Quantum in 5W-40.
PSA B71 2290 and B71 2312: both appear on Elat C2 oils – Cipe C2 and Profi Tec.
Renault RN 0720: C4 Ren Tec lists this low-ash Renault standard, qualified on its label as “with DPF; except 2.2 DCI”; see Renault RN engine oil standards.
VW 508 00/509 00, BMW LL17FE+, MB 229.71: these low-viscosity standards are listed by the 0W-20 VW Tec Blue Oil, which is specified to ACEA C5 and C6.
Ford WSS-M2C948-A/B: 5W20 Ford Eco lists this Ford standard together with ACEA C5.

Conversely, standards such as BMW LL-01 or MB 229.5 stand for full-SAPS oils, even though they are designed for long drain intervals. “Longlife” and “low SAPS” are therefore not the same thing – what counts is what the label says.

ACEA C2, C3 or C4: why the classes are not interchangeable

Each class has its own focus. C3 and C4 require a high HTHS viscosity, while C2, C5 and C6 permit lower values – for engines designed for low-viscosity oils and reduced friction. An oil with a lower HTHS viscosity therefore does not belong in an engine that calls for C3 or C4.

Likewise, a C3 oil is no substitute for a C4 oil where the manufacturer expressly requires C4 because of its stricter ash limit. Some oils meet several classes at once – in the Elat range, 5W30 Mega Tec LongLife 3 with C2/C3 and 5W30 C4 Ren Tec with C3/C4. The key point remains that the required class and standard must appear on the label.

Grade and class also go together: low-ash Elat oils range from 0W-20 to 5W-40. The right combination follows from the owner’s manual – for example, an ACEA C3 oil in 5W-30 for VW 504 00/507 00, or a C2 oil in 0W-30 for PSA B71 2312. For an overview of Elat’s 5W-30 oils, see 5W-30 engine oil by specification.

Low-SAPS engine oil for petrol engines, workshops and fleets

Low-ash oils are not just a diesel topic. The C classes are expressly intended for petrol engines with catalytic converters as well, and many manufacturers specify standards based on C classes for their petrol engines: VW 504 00, for instance, is the petrol standard of the LongLife III generation, and VW 508 00 the petrol standard for 0W-20. Direct-injection petrol engines with a petrol particulate filter, too, need the oil their owner’s manual specifies.

For workshops and fleets, two lines on the label deserve a close look: the ACEA class and the manufacturer standard. If both match the requirement, the choice is clear; if either is missing, ask before the oil goes into the engine.

Businesses of every kind – workshops, retail, industry and fleets – obtain Elat engine oils from us throughout Germany, from 1-litre bottles to 1000-litre IBCs and tanker deliveries. Technical data sheets are available on the product pages where they exist; more on supply at Supply across Germany.

Quick check before an oil change

Note the standard and grade from the owner’s manual and compare both with the ACEA class, manufacturer standard and grade on the label. If the manufacturer requires an explicit approval, check that too – and if in doubt, ask us.

Frequently asked questions

Which ACEA class does a diesel with a particulate filter need?

The vehicle manufacturer decides, usually through its own standard based on a C class. It is often C3, for example with BMW Longlife-04, MB 229.51 or VW 507 00; the PSA standards B71 2290 and B71 2312 appear on Elat C2 oils, and Renault RN 0720 (“with DPF; except 2.2 DCI”) on an oil with C4. Your owner’s manual states the binding requirement.

Is ACEA C3 the same as low SAPS?

Colloquially yes, strictly speaking no: C3 is a mid-SAPS class with a sulphated ash limit of 0.8 per cent at most. Low SAPS in the narrower sense is C4, with 0.5 per cent at most. On HTHS viscosity the two are level, with a minimum of 3.5 mPa·s.

Can I use a C3 oil if C4 is specified?

Only if the manufacturer expressly allows it. C4 limits sulphated ash more strictly than C3, and standards such as Renault RN 0720 build on it. 5W30 C4 Ren Tec lists both C3 and C4 as well as RN 0720 with the qualifier “with DPF; except 2.2 DCI”.

Do petrol engines need low-SAPS oil too?

Many do. The C classes also cover petrol engines with catalytic converters, and standards such as VW 504 00 or VW 508 00 apply to petrol engines. Whether your vehicle requires a low-ash oil is shown by the standard in its owner’s manual.

Can I use low-SAPS oil in an older car without a particulate filter?

Yes, if the oil lists the standard required for that car. 5W40 High Tec Quantum, for example, is a C3 oil that also covers the VW standards 502 00 and 505 00 as well as 505 01 for fixed service intervals. If the required standard is missing from the label, a low-ash formulation alone does not make the oil suitable.

Which low-SAPS oil suits your vehicles?

Tell us your vehicle models and the standards they require. We will recommend an Elat oil with the right ACEA C class and supply it to you nationwide.

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