Mercedes W221 Gearbox Cooler Oil Transmission Radiator Left N/S A6421800731

Mercedes W221 Gearbox Cooler Oil Transmission Radiator Left N/S is a specialized component of the lubrication system, responsible for efficiently routing oil to the radiator and maintaining stable engine operating temperatures. Thanks to its precise fit for the Mercedes W221 series design and its dedicated placement on the left side, the hose ensures a secure connection and minimizes the risk of leaks. This is a practical solution for users looking to restore the proper operation of the oil cooling system using an original component.

Specifications and technical data

• SKU: A6421800731
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6421800731
• Substitutable numbers: A6421800731, A 642 180 07 31
• Location on the vehicle: Left
• Category: Oil Coolers & Lines

Purpose and function in the oil cooling system

The oil cooler hose in the Mercedes W221 is responsible for the safe delivery and return of oil between the engine and the oil cooler, which helps maintain stable operating parameters for the power unit. This component operates under demanding thermal and pressure conditions, which is why its tightness and proper routing are crucial for protecting the engine against oil overheating and loss of lubrication. A properly functioning oil cooler hose reduces the risk of damage to bearings, the turbocharger, and other oil-lubricated components.

Fitment for Mercedes W221 and left-side placement

The offered hose has been designed with the body and drivetrain construction of the Mercedes S-Class W221 generation in mind, taking into account the specific routing of the oil system. Placement on the left side of the vehicle means that the hose geometry, the shape of the bends, and the mounting points are adapted to the factory routing of lines in this area. As a result, installation is straightforward, without the need for modifications, and the hose does not interfere with other components in the engine bay.

Performance characteristics and benefits of using an original hose

Choosing an original oil cooler hose for the Mercedes W221 allows you to maintain factory flow parameters and resistance to operational loads. In practice, this means:

• stable oil pressure in the cooler circuit,
• reduced risk of leaks at connections and joints,
• proper hose routing relative to body elements and engine accessories,
• better compatibility with factory brackets and mounts.

By maintaining the original hose geometry, the oil cooling system operates under conditions close to factory specifications, which promotes a longer service life for the power unit. Using dedicated oil cooler hoses is particularly important in premium-class vehicles, where assembly tolerances and thermal requirements are higher than in mass-market designs.

Condition, verification, and service application

The item comes from the Oil coolers and hoses category, meaning it is intended for use in engine oil lubrication and cooling systems. As a used part, it provides an economical solution for users who want to restore system functionality without the need to invest in a new component, while maintaining the original design specifications. This type of hose works well both for standard replacement of a damaged part and for repairs following an oil cooling system failure.

Before installation, a standard check of tightness and the condition of the connectors is recommended to ensure trouble-free operation after installation. Professional installation at a specialized service center further minimizes the risk of assembly errors and ensures the correct positioning of the hose in the engine bay.

Technical support and expanding knowledge about the cooling system

For users who want to better understand the impact of the oil cooler and hoses on the durability of the power unit, we recommend our guide article: Engine cooling system – overheating, repair, and used radiators. This material explains how a properly functioning cooling system – including the oil cooler – translates into operational safety and reduces the risk of costly repairs.

If you are planning a comprehensive repair or upgrade of the lubrication and oil cooling area in your Mercedes and need other elements from the same group, such as hoses, pipes, or complete oil cooler modules, check out the available parts in the Mercedes oil coolers and hoses category.

Additional information on selecting used components for popular car models is also provided in our guide: The best used car parts – a guide to the most frequently chosen original parts, which helps you make informed choices when selecting parts from the secondary market in terms of quality and cost-effectiveness.