The Mercedes SLK 2012 English owner’s manual lists 5.5 litres including the oil filter for its SLK200 and SLK250 BlueEFFICIENCY petrol entries. For the early 1.8-litre M271 cars covered here, choose an oil carrying an approval allowed by the applicable manual; viscosity alone is not the specification.
Coverage: early R172 SLK200 and SLK250 CGI/BlueEFFICIENCY petrol models with the 1,796 cc M271.861 engine. Match model type 172.448 (200) or 172.447 (250). Later 1,991 cc SLK200 M274, SLK250 CDI/diesel, SLK350, AMG and SLC models need their own application checks.
Oil capacity: what the 5.5-litre figure means
| Manual application | Oil-change quantity including filter |
|---|---|
| SLK200 BlueEFFICIENCY petrol | 5.5 litres |
| SLK250 BlueEFFICIENCY petrol | 5.5 litres |
This is the quantity for an oil change with filter renewal in the inspected manual, rather than a top-up instruction. Do not pour that amount into an engine that already contains its oil. The same page groups other SLK engines separately, so taking a figure from an SLK350 or diesel SLK250 result can give the wrong answer.
For buying purposes, a single five-litre container is less than the listed service quantity. A five-litre plus one-litre purchase, or another combination totalling at least 5.5 litres, covers that nominal amount. Container sizes and offers vary: compare the total quantity as well as the headline price. The amount actually added must still be set using the correct level-check procedure.
Which Mercedes oil approval applies?
The inspected English manual’s shared SLK200/SLK250 petrol row lists MB Approval 229.3, 229.5 or 229.51. Check the edition supplied with your car and any applicable updated requirements before ordering. This is a reference for the named early petrol models, not a statement that those three approvals are interchangeable throughout the Mercedes range.
The number identifies an approval, while “0W-40” or “5W-30” describes a viscosity grade. An online title saying “for Mercedes” does not establish either. Read the exact product name and its approval declaration, then choose the permitted grade for the conditions and vehicle guidance.
A current product example: Mobil 1 FS 0W-40
Mobil’s UK product information lists Mobil 1 FS 0W-40 with MB-Approval 229.5. It provides a specific buying option where that approval and grade suit the car. The FS name matters: do not assume another Mobil 1 product or another viscosity has the same approvals.
Affiliate link: as an Amazon Associate, Unusual Cars earns from qualifying purchases.
Search Amazon for Mobil 1 FS 0W-40Search results may include other formulations, quantities or accessories. Check the bottle and seller’s exact listing for FS 0W-40, the approval and the quantity supplied. The link opens a product search, rather than guaranteeing the fit or approval of everything displayed.
Checking the level and topping up
The manual calls for level ground, with the engine switched off for around five minutes after reaching operating temperature, or about 30 minutes if it was only run briefly and is not at normal operating temperature. Wipe and fully reinsert the dipstick before reading it; the level should lie between its marks.
Follow the car’s instructions when adding oil, recheck the level and avoid overfilling. Keep oil away from hot components. An upcoming ASSYST PLUS service is a separate matter from the present oil level: the due date does not tell you how much to top up.
What about the oil filter?
A suitable oil does not establish oil-filter fitment. Check the filter separately against the early M271 application and the current supplier catalogue. Our SLK200/SLK250 filter and spark-plug guide explains the manufacturer references and the limits of a generic SLK search.
Questions before buying
Is 229.52 automatically a better replacement for 229.5?
Do not select an oil by choosing the highest-looking number. Establish an approval permitted for the exact vehicle, then check that the particular oil carries it.
Can I use this capacity for a later 2.0-litre SLK200?
No. The 1,991 cc M274 car is a separate application. Match the early 1,796 cc petrol engine before applying this page’s quantity and oil example.
Should I buy a flushing additive with the oil?
A retailer bundle is not a maintenance requirement. This guide has not established a need for an additive or flush; choose the oil and filter on their own supported specifications.
For service planning and an invoice checklist, return to the SLK200/SLK250 R172 maintenance guide.
Explore the Mercedes maintenance hub and our SLK R172 diagnostic scanner guide.
Sources and applicability
- Mercedes-Benz SLK 2012 English owner’s manual, printed page 307 (ManualsLib): visually checked approval and capacity tables. This English document includes SLK200 and diesel entries; the North American manual is a different document.
- Mercedes manual, printed page 250: oil-level checking.
- Mobil UK: Mobil 1 FS 0W-40: current product approval declaration.
- MANN-FILTER catalogue, printed page 235: early M271 and later M274 application distinction.
Checked 20 October 2026. Capacity and approval references remain limited to the named manual and applications.
