Mercedes SL350 R230 Filters and Spark Plugs: M112 and M272

SL350 R230 parts depend on the engine. MANN lists C 3698/3-2 air filtration for M112.973 and M272.966, but two C 3689 filters for the later M272.968. NGK lists 12 plugs for the M112 and six for the M272.

Coverage: SL350 R230 with M112.973, M272.966 or M272.968, subject to the engine and source conditions below. R129, R231, SL500 and AMG versions require separate specifications.

Identify the application first

MANN’s catalogue dates help identify the rows, but are not exact registration cut-offs. Check the engine and model details from the vehicle documentation or with the supplier. The two 3.5-litre entries should not be collapsed into one universal service kit.

Engine air filters: the later M272 changes the reference

The current C 3698/3-2 application page names the first two engines. The C 3689 page names M272.968 and explicitly states a two-piece requirement. Check both reference and quantity.

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M112.973 and M272.966 applications

Later M272.968 application: two C 3689 pieces required

These links open searches. Confirm whether the chosen item supplies an individual element or a complete set, and match the manufacturer’s application. A photograph showing two filters is not proof that the price includes both.

Oil filter: HU 718/5 x

MANN’s current product page and printed R230 table list HU 718/5 x for all three named SL350 engines. Preserve the full reference when checking the supplier item; similar HU 718 references should not be assumed interchangeable.

For eBay browsing, add or select the exact vehicle and inspect the individual listing’s complete reference and compatibility information. Resolve any disagreement with the supplier before ordering.

The graphic is an affiliate category link. A saved vehicle does not establish that every displayed result fits. The later M272.968 oil guide covers that engine’s independently checked oil quantity and approval; earlier versions need their own applicable oil specification.

Cabin filtration: MANN CUK 2241-2

MANN’s current CUK 2241-2 page lists the M112.973, M272.966 and M272.968 SL350 applications. Its printed catalogue also gives CUK 2241-2 as activated-carbon cabin filtration for the R230 range.

Keep the complete reference, including -2, and confirm the actual supplied contents. Do not copy a cabin-filter number from the next-generation R231, which has separate catalogue entries.

Spark plugs: 12 for M112, six for M272

The UK 2024 catalogue gives March 2003–April 2006 for its 3.7-litre row and March 2006–April 2013 for the 3.5-litre row. Those dates differ from MANN’s ranges. Retain the named engine application rather than turning either date range into a UK registration boundary.

Check the complete reference and whether a quote covers the whole set. A V6 badge is not a reason to order six plugs for the M112. Equally, the M112’s quantity should not be carried into an M272 order.

These rows establish applications, not a fitting torque, universal renewal interval or fault diagnosis. Keep plug replacement separate from investigating a misfire, coil fault or another running problem.

Fuel filter and service-kit contents

MANN’s printed table lists WK 720 for all three named SL350 engines. Treat it as an application reference, not evidence that renewal is due at every A or B service.

Compare applicable maintenance requirements with the dated history before adding work. Ask the invoice to identify engine air, oil, cabin and fuel filtration separately. The SL350 R230 maintenance guide helps organise the quotation and service records.

Explore the Mercedes maintenance hub. For warning lamps, gearbox, roof or suspension investigation, see our SL R230 diagnostic scanner guide.

Sources and application limits

• MANN C 3698/3-2 and MANN C 3689: separate engine applications and later quantity.
• MANN HU 718/5 x and MANN CUK 2241-2: named applications.
• MANN 2024–26 catalogue, printed page 234 / PDF page 290: complete R230 rows, visually checked.
• NGK UK 2024, printed page 48 / PDF page 50: plug references and quantities, visually checked.

Checked 20 October 2026. Parts applications do not establish universal renewal intervals, installation procedures or suitability for other SL engines.

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