Service A / Service B
About 25,000 km or 1 year (ASSYST)
25 000 km
12 months
Oil and filter at each service; Service B adds filters and wider checks. The ASSYST indicator prevails.
Source [1]C257 · 2018–2023
Mercedes CLS CLS 400 d 4MATIC C257 · 340 hp (2018 to 2023)
The Mercedes CLS CLS 400 d 4MATIC of the C257 generation uses the OM656 2.9 I6 d diesel engine with 340 hp.
Choose an engine
Identify the car and prepare its maintenanceTechnical specifications
- Fuel
- Diesel
- Power
- 340 PS / 250 kW
- Displacement
- 2 925 cm³
- Cylinders
- 6
- Engine code
- OM656 2.9 I6 d
- Period covered
- 2018–2023
- Documented market
- Europe
Transmission
- Automatic · 9 speeds
Figures apply to the cited configuration and market; equipment and transmissions may vary by production date.
Specification source : [1] AutoKarnet
This version
340 hp (250 kW), 4MATIC all-wheel drive, 9-speed automatic. Built from 2018 to 2023.
AutoKarnet advice
In the range
It is the most powerful diesel version of this generation. The OM656 2.9 I6 d engine is also fitted to: Mercedes Classe E (W213), Mercedes Classe S (W222), Mercedes Classe S (W223), Mercedes GLE / ML (GLE W167), Mercedes GLS (X167), Mercedes Classe G (W463 (2018)).
AutoKarnet advice
Maintenance and records
Brake fluid
Every 24 months
24 months
Time-based replacement, whatever the mileage.
Source [1]Questions about this version (2)
Which engine is in the Mercedes CLS CLS 400 d 4MATIC C257?
The OM656 2.9 I6 d diesel engine (2 925 cc), 340 hp (250 kW).
AutoKarnet advice
Which oil for the Mercedes CLS CLS 400 d 4MATIC?
A MB 229.5 / 229.51 / 229.52-approved oil suited to the OM656 2.9 I6 d engine.
AutoKarnet advice
Documentary sources
- [1] Rédaction AutoKarnet
AutoKarnet · FR · Europe · Synthèse éditoriale AutoKarnet · Accessed 09/10/2026