2005 Bentley Arnage LWB Complete Maintenance Schedule & Service Guide

Key Takeaways

• Factory maintenance interval: Annual service or every 10,000 miles (approximately 16,000 km), whichever comes first, with a 6-month/16,000 km service check also cited for this model year
• Engine: 6.75L twin-turbo V8, rear-wheel drive with 4-speed automatic transmission
• Service schedule progression: The Arnage follows a rotating service type schedule: Type A at 10,000 miles, Types A & B at 20,000 miles, Types A & C at 30,000 miles, and a major Type A, B, C & E service at 60,000 miles
• Spark plugs: Replacement at 30,000-mile intervals as part of Service Type C
• Coolant: Replacement recommended at 30,000-mile/3-year intervals
• Brake fluid: Replacement at 20,000-mile intervals as part of Service Type B
• Critical 15-year item: ABS/ASC modulator relays require replacement after 15 years regardless of mileage
• Warranty: 3-year/unlimited mileage factory coverage from new

Introduction

The 2005 Bentley Arnage LWB represents the pinnacle of Bentley's flagship sedan, offering extended rear passenger space alongside the legendary 6.75L twin-turbo V8. As the long-wheelbase variant, the LWB prioritizes rear-seat comfort and luxury while sharing the same mechanical foundation as other Arnage models.

As a hand-built luxury motorcar of exceptional complexity, proper maintenance is essential for preserving performance, reliability, and value. This maintenance schedule is compiled from factory guidance and specialist references. The LWB variant shares its comprehensive service schedule with other 2005 Arnage models, and all guidance reflects the rear-wheel-drive configuration.

Factory Recommended Service Schedule

Service Interval

The 2005 Bentley Arnage follows a structured service schedule based on mileage or time, whichever comes first. The primary interval is annual service or every 10,000 miles (approximately 16,000 km) . Some documentation also indicates a 6-month service check, likely for high-mileage or fleet vehicles.

The first year of Bentley service was complimentary for original owners . Following the vehicle inspection, owners are informed of any components not meeting specification, at which time they can approve any necessary repairs.

Service Schedule Progression

The Arnage's service schedule follows a rotating series of service types, each building upon the last to ensure comprehensive coverage :

After reaching 100,000 miles, the service schedule repeats .

Critical 15-Year Item

A specific, crucial maintenance item is scheduled after 15 years, regardless of mileage: the replacement of the ABS/ASC modulator relays. This is a critical safety measure, as these relays are vital for the vehicle's advanced braking and stability control systems . For a 2005 Arnage, this would have been due in 2020.

Warranty Coverage

Every new 2005 Bentley Arnage came with a 3-year/unlimited mileage factory warranty . Original owners could extend the factory warranty by an additional two years. This extension is transferable to private buyers and features unlimited mileage, unlimited claims value, and Bentley roadside assistance .

Service Type A: The Annual Foundation

This is the most frequent service, performed annually or every 10,000 miles :

Replacements:

• Engine oil and oil filter
• Transmission oil
• New sealing washer for engine sump plug
• Pollen filters
• Keyless remote batteries

Lubrication and Cleaning:

• Lubricate gear range selector rod
• Remove foreign matter from: radiator, condenser, engine oil cooler, steering system oil cooler, charge coolers, and gearbox oil cooler

Comprehensive Inspection:

• Hydraulic system, exhaust system, braking system
• Body drains
• Engine mounts, gearbox mounts, sub-frame mounts
• Engine drive belt
• Fuel system
• Turbocharger rubber hoses
• Steering column universal joints, couplings, steering rack flexible gaiters, track rod, front axle ball joints
• Drive-shaft gaiters
• Bottom radiator hose
• Tire treads and tire pressure
• Parking brake and cables
• Coolant hoses and clips, coolant levels
• Washer fluid, central hydraulic system reservoir fluid, brake fluid
• ABS modulator
• Water cooled charge cooler fan and pump, E-box, ECM cooling fan
• Wiper blades, batteries, spare wheel
• Seat belts, lights and horn, steering

Service Type B: Braking and Undercarriage Focus

Performed at 20,000-mile intervals (20k, 40k, 60k, 80k, 100k miles), Service Type B adds comprehensive checks of the braking system and undercarriage components :

• Replace brake fluid
• Lubricate door check mechanisms and clevis pins
• Inspect: gearbox actuator breather, undercarriage, final drive, brake calipers and dust seals, brake discs and parking brake drums, remote control locking and anti-theft system, and bodywork

Service Type C: Spark Plugs, Coolant, and Transmission

Performed at 30,000-mile intervals (30k, 60k, 90k miles), Service Type C includes :

• Lubricate gear range selector rod
• Replace transmission oil intake strainer
• Lubricate height control valve ball joint
• Lubricate brake push rod clevis pin
• Replace spark plugs
• Replace coolant
• Inspect dampers and front and rear convoluted seals

Service Type D: Air Filtration System

Performed at 50,000-mile intervals (50k, 100k miles), Service Type D focuses on the air filtration system :

• Replace air filter elements
• Replace secondary air injection filter

Service Types E and F

Service Type E (60,000 miles): Includes inspecting gas charge pressure in the hydraulic accumulator, replacing leak detection pump filter, replacing brake caliper seals, replacing brake caliper flexible hoses, and replacing final drive oil .

Service Type F (100,000 miles): Includes replacing main fuel filter, replacing evaporative loss control canister, replacing engine drive belt, and replacing oxygen sensors, along with inspecting the induction system .

Engine Oil Change Guidance

The 2005 Arnage LWB is equipped with the 6.75L twin-turbo V8, a powerhouse with substantial lubrication requirements.

Oil Capacity and Specifications

The 6.75L V8 requires high-quality synthetic oil meeting Bentley specifications. The engine has a substantial oil capacity of approximately 9.4 liters with a filter change. Always verify the exact viscosity required for your specific engine variant and ensure the oil meets Bentley/VW approvals.

Recommended Oil Change Interval

• Factory recommendation: Annual or every 10,000 miles (Service Type A)
• Conservative owner guidance: Given the vehicle's age, many specialists suggest more frequent changes—6,000 to 8,000 miles—particularly if the car is driven infrequently or in stop-start conditions

Oil Quality Notes

Regular oil changes are particularly important for the 6.75L V8. Using incorrect oil can lead to premature engine wear and reduced performance. The engine is known to be sensitive to oil quality, and proper lubrication is essential for the twin-turbo system's longevity.

Transmission Service Guidance

The 2005 Bentley Arnage LWB is a rear-wheel-drive vehicle with a 4-speed automatic transmission . This is a GM 4L80-E unit, a robust and well-proven transmission design.

Service Schedule

• Transmission oil is replaced as part of Service Type A (every 10,000 miles)
• The transmission oil intake strainer is replaced at Service Type C intervals (30,000 miles)

Conservative Owner Guidance

• If service history is unclear, consider having the transmission fully serviced by a specialist
• If shifting becomes rough, delayed, or accompanied by unusual noises, have the transmission inspected immediately

Spark Plug Timing

Service Schedule: Spark plugs are replaced as part of Service Type C at 30,000-mile intervals (30k, 60k, 90k miles) .

Owner accounts indicate that spark plug replacement on the 6.75L V8, while sometimes described as potentially difficult, can be completed in under an hour by a competent mechanic with the right tools . This underscores the importance of using a qualified technician familiar with the engine layout.

Technical Specifications

Coolant Service Timing

Service Schedule: Coolant is replaced as part of Service Type C at 30,000-mile intervals (30k, 60k, 90k miles) .

Coolant Type

The Arnage uses a glycol-based antifreeze/coolant, typically a 50/50 mix of antifreeze and distilled water.

Owner Guidance

Given the age of the 2005 Arnage, any coolant that has been in service beyond 4-5 years should be replaced proactively. Proper cooling system maintenance is essential for the 6.75L V8's longevity.

Brake Fluid Recommendations

Brake fluid is a critical safety component that degrades over time by absorbing moisture from the atmosphere.

Service Schedule

Brake fluid is replaced as part of Service Type B at 20,000-mile intervals .

Conservative Owner Guidance

While the factory schedule includes brake fluid replacement at 20,000-mile intervals, a conservative approach is to flush brake fluid every 2 years regardless of mileage to prevent moisture absorption and corrosion.

Brake Pad and Disc Inspection

The Arnage is a heavy vehicle with substantial braking requirements. Front brake pads may require replacement more frequently than typical passenger cars, potentially every 15,000–25,000 miles depending on driving style. Rear brake pads, as noted in specialist accounts, are relatively straightforward to replace .

Additional Maintenance Considerations

Service History Importance

Maintaining a comprehensive service history is critically important for the 2005 Arnage LWB. Well-maintained examples with full main dealer or specialist service history are significantly more desirable and valuable.

Known Long-Term Considerations

Based on ownership experience with this model generation, several areas warrant attention :

Cooling System: The auxiliary water pumps used for intercooling can fail and are labor-intensive to replace. Regular inspection of cooling system components is recommended during annual services.

PCV Valve: If the engine sounds rough at idle, the positive crankcase ventilation (PCV) valve may be at fault. This valve is buried beneath the turbo plumbing, making replacement labor-intensive.

Turbocharger Components: Wastegates on higher-mileage Arnage examples can develop leaks. Turbocharger rubber hoses are inspected as part of the annual service.

Electrical Systems: As with many luxury vehicles of this era, electrical components can become a source of issues as the vehicle ages. Proper battery maintenance and professional diagnosis of electrical faults are important.

Drive Belt

The engine drive belt is inspected at every Service Type A and is replaced as part of the 100,000-mile Service Type F .

Batteries

The Arnage uses twin batteries. These should be inspected during every service. The vehicle should be kept on a trickle charger if not used weekly to maintain battery health and prevent electrical system issues.

High-Mileage Maintenance Planning

For 2005 Arnage LWB examples approaching or exceeding 75,000 miles:

1. Major service (60,000-mile type): If not documented, consider the comprehensive A, B, C, and E service
2. Coolant flush: Complete system flush with fresh coolant
3. Brake fluid flush: Full hydraulic system flush
4. Transmission service: Replace fluid and strainer if not documented
5. Spark plugs: Replace if not done within the last 30,000 miles
6. Drive belt: Inspect and replace if more than 5-6 years old
7. ABS/ASC relays: Confirm replacement has been performed (due at 15 years)
8. PCV system: Inspect and replace if showing signs of failure
9. Turbocharger wastegates: Inspect for leaks on higher-mileage examples

Long-Term Ownership Considerations

The 2005 Bentley Arnage LWB rewards diligent maintenance. As a low-production, hand-built motorcar:

• Oil changes: Regular oil changes with the correct viscosity and approval are essential for the longevity of the 6.75L V8
• Cooling system: Regular coolant changes and inspection of auxiliary water pumps are essential
• Specialist care: Given the vehicle's complexity, using qualified specialists familiar with the Arnage is strongly recommended
• Documentation: Maintain a comprehensive service history to help preserve resale value