The Mercedes CLK handbook lists 8.5 litres for a CLK320 CDI engine-oil change including the oil filter. For a car with a diesel particulate filter (DPF), its oil table includes MB 229.31 and 229.51. Choose the required approval first, then a viscosity permitted for your car.
Covered cars: CLK320 CDI C209 coupé and A209 cabriolet, model types 209.320/420, with the 2,987 cc OM642.910 V6 diesel, 165 kW / 224 hp. MANN lists its CLK320 CDI application from May 2005 to October 2009; catalogue dates are not UK registration cut-offs. The petrol CLK320 and earlier CLK270 CDI use different engines.
CLK320 CDI oil capacity at a glance
| Question | Answer |
|---|---|
| Oil-change quantity including filter | 8.5 litres in the 2008 CLK manual |
| Engine covered | OM642.910 3.0-litre V6 diesel |
| MANN oil-filter reference | HU 821 x for the listed CLK320 CDI application |
| Is 8.5 litres a top-up amount? | No. It is the listed oil-change quantity including the filter. |
| How much should I buy? | Two 5-litre containers total 10 litres; compare the price with other pack combinations covering 8.5 litres. |
Use the quantity to plan the purchase. During the work, establish the final level using the handbook’s method rather than pouring in a whole purchased pack. The amount needed for a top-up is determined by the measured level or applicable display instruction.
Which Mercedes oil approval does it need?
The manual separates diesel cars with and without a DPF. For the CLK320 CDI with DPF, it lists 228.51 / 229.31 / 229.51. Its no-DPF row lists a wider selection. For shopping, the practical route is to establish the specification in your own handbook and choose a product carrying that approval.
The DPF distinction matters more than an advert saying “Mercedes diesel oil”. A 5W-30 description states viscosity; it does not establish a Mercedes approval. Equally, a newer approval number on a bottle does not by itself explain your car’s requirement.
Mobil 1 ESP 5W-30: a named buying option
Mobil’s current UK product page lists MB-Approval 229.51 and 229.52 for Mobil 1 ESP 5W-30. That makes it a buying option where your CLK requires or permits 229.51 and the 5W-30 grade is suitable. The 229.51 approval is the relevant match to the 2008 handbook.
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Search Amazon for Mobil 1 ESP 5W-30The link searches for the named product. Check the exact bottle’s approval, formulation, size and seller before ordering; search results may include other Mobil products. Compare the total cost of enough oil for the change, including delivery, rather than the price of one container.
Oil filter and other service parts
MANN’s HU 821 x product page lists CLK320 CDI, OM642, 2,987 cc and 165 kW. Retain the full reference and check the seals supplied. Our CLK320 CDI filter guide explains the air, oil, cabin and diesel-fuel options together.
If a workshop is carrying out the change, agree supplied parts in advance and ask it to record the oil product, approval and quantity on the invoice. Keep that with the mileage and service date.
Three common oil-buying mistakes
- Using petrol CLK320 figures: it is a different engine. Keep CDI and OM642.910 in the enquiry.
- Buying by viscosity alone: confirm the MB approval on the exact oil product.
- Treating capacity as a top-up instruction: the full oil-change quantity is not the amount to add to an engine already containing oil.
For the full visit and UK service-price examples, read our CLK320 CDI maintenance guide.
Find other models in the Mercedes maintenance hub. For fault-reading equipment, use our Mercedes diagnostic scanner guides and check exact vehicle and function coverage.
Sources and checks
- Mercedes 2008 CLK manual, printed page 339 — diesel approvals and oil-change quantity including filter.
- Mobil UK: Mobil 1 ESP 5W-30 — current product approvals, checked 23 October 2026.
- MANN HU 821 x manufacturer application — CLK diesel filter reference.
Checked 23 October 2026. The 2008 Mercedes manual cited here is a German-market edition reproduced by ManualsLib. Use the handbook and service booklet supplied with your car for its equipment and maintenance schedule. For corrections, contact Unusual Cars; keep VINs and registration details private.
