2018 BMW 640i Convertible Preventive Maintenance & Service Schedule

Key Takeaways

• The 2018 BMW 640i Convertible (F12 chassis) is powered by the N55 3.0L turbocharged inline-six engine, with an oil capacity of 6.5 liters .
• BMW employs a Condition Based Service (CBS) system that uses sensors and driving data to calculate maintenance needs based on actual driving conditions rather than fixed intervals .
• A conservative synthetic oil change interval is recommended at 5,000 miles to maximize engine longevity and turbocharger health .
• Brake fluid requires replacement at intervals specified by the CBS system and should be flushed regularly to prevent moisture contamination .
• The vehicle carries a 48-month/50,000-mile basic and powertrain warranty, with 36 months/36,000 miles of scheduled maintenance coverage from the original in-service date .
• The convertible top mechanism, while not requiring specific service intervals, should be inspected periodically for proper operation and seal condition.

Understanding BMW's Condition Based Service (CBS) System

The 2018 BMW 640i Convertible utilizes BMW's Condition Based Service (CBS) system, an intelligent maintenance monitoring approach that uses onboard sensors and algorithms to calculate service intervals based on actual driving conditions rather than fixed mileage or time schedules . The system monitors factors such as driving style, trip duration, engine temperatures, and component wear to determine when service is needed .

Service information is stored in the vehicle's electronic systems, and the car displays service interval warnings through the instrument cluster and iDrive system . This adaptive approach ensures parts are serviced or replaced only when nearing the end of their useful life, reducing unnecessary maintenance while preventing missed service items .

Factory Maintenance Coverage

The 2018 BMW 640i Convertible was covered by BMW's maintenance program for 36 months or 36,000 miles from the original in-service date . This coverage includes scheduled maintenance as determined by the CBS system. The vehicle also carries a standard 48-month/50,000-mile warranty covering basic and powertrain components, with corrosion perforation warranty extending to 144 months/unlimited miles .

For vehicles beyond this coverage period, owners should plan for out-of-pocket maintenance. The estimated cost of maintenance increases significantly in the fifth year of ownership as major service items become due .

OEM Factory Maintenance Schedule

The following maintenance items represent the recommended service milestones for the 2018 BMW 640i Convertible. Exact intervals are determined by the vehicle's CBS system based on driving conditions .

Engine Oil and Filter Change

The 2018 640i Convertible uses the N55 3.0L turbocharged inline-six engine, which has an oil capacity of 6.5 liters . BMW's CBS system will indicate when an oil service is due, with typical intervals around 10,000 miles or 12 months depending on driving conditions.

Oil Specifications:

• BMW-approved synthetic oil meeting Longlife specifications
• The N55 engine requires oil with specific BMW approvals to maintain warranty coverage
• Viscosity should be selected based on climate and driving conditions as specified in the owner's manual

Conservative Owner Guidance:

Motor oil is the single most important element in keeping your engine healthy . Some independent references recommend changing synthetic motor oil every 5,000 miles for optimal engine protection, particularly for turbocharged engines like the N55 . More frequent changes are advisable if you regularly:

• Drive in severe stop-and-go traffic
• Engage in aggressive or spirited driving
• Operate in dusty conditions
• Make frequent short trips

Always replace the oil filter at every oil change .

Brake Fluid Service

Brake fluid is a hydraulic fluid that must be maintained to ensure proper braking performance . BMW's CBS system monitors brake fluid condition and will indicate when service is due.

Fluid Specification:

• BMW-approved brake fluid
• DOT4 specification is commonly recommended for this vehicle
• BMW also offers a low-viscosity formula ideal for extreme braking conditions

Conservative Owner Guidance:

Brake fluid should be changed at the interval indicated by the CBS system . Additionally, BMW generally recommends that brakes be serviced at least once every 12,000 miles or 12 months, including inspection of brake pads, rotors, and the parking brake mechanism. Brake fluid absorbs moisture from the atmosphere over time, which lowers its boiling point and compromises braking performance.

Spark Plug Service

The N55 engine uses high-performance spark plugs to ignite the fuel-air mixture in the combustion chamber . BMW's CBS system will indicate when spark plug replacement is needed based on driving conditions and mileage.

Service Detail:

Spark plugs are a critical component for engine performance and fuel efficiency. Worn plugs can lead to rough idling, reduced fuel economy, and hesitation during acceleration. The N55 engine uses 6 spark plugs .

Differential Fluid Service

Differential oil lubricates and assists in the heat dissipation of the differential . It should be checked for level and changed as per the owner's manual recommendation .

Drivetrain Note: The 2018 BMW 640i Convertible is available in both rear-wheel-drive and xDrive (all-wheel-drive) configurations . Differential fluid service requirements may differ between these drivetrains. The xDrive model includes front and rear differentials, while the rear-wheel-drive model has only a rear differential.

Wheel Bearing Maintenance

Wheel bearing grease lubricates the bearings that support the weight and heat generated by the spinning of the wheels . Some references recommend cleaning and repacking wheel bearings once a year as preventive maintenance .

Common Long-Term Ownership Considerations

Cooling System

The N55 engine uses a sophisticated cooling system with an electric water pump. Cooling system components should be inspected regularly as the vehicle ages, and coolant should be replaced at intervals specified by the CBS system or per the owner's manual.

Convertible Top Mechanism

The 2018 640i Convertible features a retractable hardtop or soft top depending on the specific configuration. While there is no specific maintenance interval for the top mechanism, periodic inspection of seals, hinges, and hydraulic components is advisable.

Service Interval Display

The 2018 BMW 640i Convertible includes a service interval warning system in the instrument cluster, which will notify the driver when maintenance is approaching or due .