For a petrol CLK320 C209 coupé or A209 cabriolet, record the complete ASSYST reminder and check the M112 V6 service history before booking. Two details matter when comparing quotes: Mercedes lists an 8-litre oil change with filter, and NGK lists 12 spark plugs for the M112.955 application.
Coverage: petrol CLK320 C209 coupé and A209 cabriolet with the 3,199 cc M112.955 V6, model types 209.365/465. The older C208/A208 CLK320, CLK320 CDI, CLK350 and other engines require separate specifications.
Make sure the guide matches your CLK320
| Identifier | Covered application |
|---|---|
| Engine | M112.955 petrol V6, 3,199 cc |
| Model types | 209.365 coupé / 209.465 cabriolet |
| MANN output | 160 kW / 218 hp |
| MANN application dates | May 2002–June 2005 |
The CLK320 name was also used on the older 208-series petrol car and the later CLK320 CDI diesel. Confirm the model and engine from vehicle documentation or a supplier check. A “320” badge or a registration year does not establish a complete parts specification.
The M112 and later M272 V6 applications also need their own checks. A six-cylinder engine does not automatically mean six spark plugs, and a service kit for another CLK engine may have different contents.
Read the original CLK ASSYST reminder
The 2004 Mercedes manual calls the system ASSYST. It shows A/B service types with time or distance information, including due and overdue messages. Record the full display when requesting a quotation.
Ask the garage to identify the actual inspections and additional work due using the car’s applicable service information and history. The service letter cannot establish when its plugs, brake fluid or individual filters were last renewed.
For background, see Mercedes Service A explained and Service B explained. Keep the CLK’s own manual and records central to the final job list.
The records worth finding before the next visit
| Item | Look for this on the invoice |
|---|---|
| Engine oil and oil filter | Actual oil product, MB approval, quantity and complete filter reference. |
| Spark plugs | Full reference, quantity fitted, date and mileage. |
| Engine air filtration | Complete reference and supplied contents. |
| Cabin filtration | Steering side, climate system and each element renewed. |
| Brake fluid | Renewal date, distinct from a fluid-level check. |
| Transmission | Gearbox identity and previous fluid/filter work. |
If history is incomplete, ask the workshop to separate scheduled requirements from work proposed to establish a baseline. That distinction makes the quotation easier to compare and gives the next owner a useful record.
Budget for the V6’s oil and plugs
The manual’s 8.0-litre engine-with-filter replacement reference is larger than the adjacent CLK200 Kompressor entry. Our CLK320 oil guide explains the applicable approval list, purchase quantities and a named oil option.
NGK lists 12 PFR5G-11 plugs for this M112.955 application. Check the quantity supplied in a quote or retail pack. The CLK320 filters and spark-plugs guide also checks the engine air filter, oil filter and climate-dependent cabin filtration.
A service kit may be convenient, but its contents should match the work already identified. Do not assume a package called “full service” contains the correct quantity of plugs or every cabin-filter element for the fitted equipment.
Calendar maintenance and storage
The inspected Mercedes manual specifies brake-fluid renewal every two years. Retain the actual renewal date, and confirm the requirements applicable to the car.
It also says the timed service indicator does not record periods when the battery is disconnected. Keep those dates and tell the workshop so elapsed time can be accounted for, particularly on a seasonally used cabriolet.
Clearing a message and resetting the service record are different actions. The manual describes the workshop resetting the indicator after the service work; a reset alone does not show what was done.
Ask for an itemised quotation
Supply the full reminder, mileage, engine details and last invoices. Ask for inspections, renewals, parts, labour and VAT to be clear. Keep separate symptoms—such as a starting problem, warning lamp or roof fault—identifiable as diagnostic work.
After the visit, retain the invoice and service-record update together. Specific dated entries are more useful than a broad service label when deciding what is due next.
Explore the Mercedes maintenance hub. For warning lamps, gearbox or cabriolet roof investigation, use our CLK W209 diagnostic scanner guide.
Sources and coverage
- Mercedes 2004 CLK manual, printed pages 265–266 / PDF pages 268–269: ASSYST and time accounting.
- Mercedes manual, printed pages 414–416 / PDF pages 417–419: oil reference and brake fluid.
- MANN 2024–26 catalogue, printed page 212 / PDF page 268: engine and equipment branches.
- NGK UK 2024, printed page 46 / PDF page 48: plug reference and quantity.
Checked 20 October 2026. The Mercedes-hosted English 2004 CLK manual includes coupé and cabriolet sections. Match the manual, market and service information applicable to your car. Manufacturer catalogue dates identify application ranges, not exact UK registration boundaries.
