2004 Acura 3.5RL Complete Maintenance Schedule & Service Guide

Key Takeaways

• The 2004 Acura RL uses a timing belt, NOT a chain. The 3.5L C35A V6 is an interference engine – if the timing belt breaks, the pistons will strike the valves, causing catastrophic engine damage requiring complete engine replacement. The recommended replacement interval is 105,000 miles or 84 months (7 years), whichever comes first .
• Premium fuel (91 octane or higher) is recommended. The 2004 RL's 3.5L V6 is designed to run on premium unleaded gasoline for optimal performance and engine longevity.
• The 5-speed automatic transmission requires diligent maintenance. The 2004 RL's transmission shares the 4-speed design of earlier KA9 RLs, but regular fluid changes are essential. The Severe Conditions schedule calls for fluid replacement at shorter intervals for vehicles driven in mountainous areas, stop-and-go traffic, or extreme temperatures .
• Brake fluid replacement is time-sensitive. Acura requires brake fluid replacement every 3 years, regardless of mileage, due to its hygroscopic nature (absorbs moisture, reducing boiling point and causing internal corrosion) .
• The 2004 model year is unique. It was the first production saloon car to offer satellite radio as standard equipment and marked the end of Acura's use of numeric engine displacement designations . 2004 RLs with very low mileage exist (e.g., 65k mile examples), making time-based maintenance intervals critical .

Engine & Drivetrain Overview

The 2004 Acura 3.5RL (chassis code KA9) is the final year of the first-generation RL. It is powered by the C35A 3.5-liter, 24-valve, SOHC V6 engine producing 225 horsepower and 231 lb-ft of torque. All 2004 RL models are equipped with a 4-speed automatic transmission and feature front-wheel drive.

Key Specifications :

Critical Warning: The C35A engine uses a rubber timing belt, not a metal timing chain. This is an interference engine – if the timing belt breaks while the engine is running, the pistons will strike the open valves, resulting in bent valves, damaged pistons, and typically requiring complete engine replacement . Timing belt replacement on schedule is not optional.

Selecting the Correct Maintenance Schedule

The 2004 Acura RL owner's manual provides two maintenance paths: Normal Conditions and Severe Conditions .

Severe Driving Conditions (Use This Schedule If Any Apply)

Select the Severe Conditions Maintenance Schedule if you regularly drive under any ONE of the following conditions:

> Note: Canadian owners must follow the Severe Conditions Maintenance Schedule . U.S. owners who only occasionally drive under "severe" conditions may follow the Normal Conditions schedule .

Factory Maintenance Schedule

Normal Conditions Schedule

The following schedule is based on OEM documentation. Service at the indicated distance or time, whichever comes first .

Severe Conditions Schedule

Under severe driving conditions, many service intervals are shortened :

Engine Oil Change Schedule

Factory Requirements

Engine Oil Specifications :

• Viscosity: SAE 5W-30 premium-grade detergent oil
• Certification: API (American Petroleum Institute) certified
• Capacity (service fill with filter): 4.6 US quarts (4.6 liters)
• Capacity (dry fill total): 5.3 US quarts (5.0 liters)
• Drain plug torque: 33 ft-lbs

Owner Guidance:

• Check the engine oil level and coolant level at each fuel stop.
• The oil filter should be replaced at every oil change.
• Your Acura does not require any oil additives.
• If 5W-30 oil is not available, consult your owner's manual for temporary alternatives .

Timing Belt – The Most Critical Service

The C35A V6 engine requires timing belt replacement on a strict schedule. This is the single most important maintenance item for the 2004 Acura RL.

Why Timing Belt Replacement Is Critical

The C35A engine is an interference engine. This means the pistons occupy the same space as the valves at certain points in the combustion cycle. If the timing belt breaks, the pistons will strike the open valves. The result is bent valves, damaged pistons, and usually a cylinder head that needs complete rebuilding (or engine replacement). As one timing belt manufacturer explains: *"When this happens, on most engines the valves interfere with the pistons. As a result, valves can be broken with possibly even more severe and expensive damage to pistons, cylinders, etc."*

Age vs. Mileage – Owner Debate

For the 2004 RL (now over 20 years old), there is community debate about whether age alone triggers replacement:

Owner Guidance: For a 2004 RL with unknown maintenance history, replace the timing belt immediately. If you have documentation showing the belt was replaced within the last 7 years or 60,000 miles, you may wait. When in doubt, replace it – the cost of replacement (typically $800-$1,200) is far less than an engine replacement ($2,500-$4,000+) .

Owner Guidance for Timing Belt Service (The "Full Job")

When replacing the timing belt, replace these components at the same time due to overlapping labor:

• Timing belt itself (Dayco 95279 is a compatible aftermarket option)
• Timing belt tensioner
• Water pump (driven by the timing belt)
• Camshaft and crankshaft seals (prevent future oil leaks)
• Drive belts (serpentine belt must be removed anyway)
• Engine coolant (requires draining to replace the water pump)

Automatic Transmission Service

The 2004 Acura RL is equipped with a 4-speed automatic transmission. The transmission uses a specific fluid type and requires regular service.

Owner Guidance:

• Use only genuine Honda/Acura ATF if possible. These transmissions are sensitive to non-spec fluid .
• A single drain-and-fill replaces only about 3 quarts of the total 8.6-quart capacity. For a more complete fluid exchange, perform multiple drain-and-fill cycles with short drives in between (the "3X method").
• If you don't have a record of the last transmission fluid change, do one now.
• Do not overfill the transmission – follow the dipstick marks carefully.

Spark Plug Replacement

The 2004 Acura RL uses platinum-tipped spark plugs designed for extended service life.

Owner guidance: The factory spark plugs are long-life platinum or iridium units. Replacement at 105,000 miles aligns with the timing belt service schedule, making it efficient to perform both services together. If you notice rough idle, misfires, or decreased fuel economy, have the plugs inspected regardless of mileage.

Coolant Service

Owner guidance:

• The 2004 RL uses the blue Honda Type 2 coolant. Using non-specified coolant can cause corrosion of aluminum engine components.
• For a 2004 model that has not had a documented coolant change, schedule a flush and refill regardless of mileage – the corrosion inhibitors degrade over time .
• Do not add straight antifreeze or water; use a pre-mixed 50/50 coolant or mix with distilled water only.

Brake Fluid Replacement

Why this matters: Brake fluid is hygroscopic – it absorbs moisture from the air over time. This moisture lowers the fluid's boiling point (which can cause brake fade under hard braking) and promotes internal corrosion of the brake system (calipers, master cylinder, ABS modulator) .

Owner guidance:

• A complete system flush (draining old fluid from the bleeder screw at each caliper) is required. Topping off the reservoir is NOT sufficient.
• Check the brake fluid level in the reservoir monthly.
• DOT 5 fluid is silicone-based and will damage your RL's braking system .

Front Differential Service

The 2004 RL's drivetrain includes a front differential that requires periodic fluid service.

Owner guidance: Use genuine Honda differential fluid or a high-quality synthetic gear oil meeting the correct viscosity specification. Under severe driving conditions (mountain driving, trailer towing, stop-and-go traffic), more frequent changes are recommended .

Drive Belts & Air Filters

Owner guidance: The 2004 RL uses a serpentine drive belt that powers the alternator, power steering pump, and A/C compressor. Inspect belts for cracking, fraying, glazing (shiny, hardened surface), or squealing noises on startup – any of these signs indicate the belt should be replaced . Most owners replace the drive belt during the timing belt service (every 105,000 miles) because labor costs are shared .

Power Steering Fluid

Owner guidance: Using the wrong fluid can damage power steering system seals and components. Always use genuine Honda power steering fluid when possible.

Additional Specifications

High-Mileage & Long-Term Ownership Considerations (100k+ Miles)

For a 2004 Acura RL that has surpassed 100,000 miles or is now over 20 years old, consider these additional factors:

> Age is a major factor for the 2004 RL. This vehicle is now over 20 years old. Time-based maintenance is just as critical as mileage-based service. Rubber components – including the timing belt, coolant hoses, and suspension bushings – degrade from heat cycling and ozone exposure, even if the car is driven infrequently .

Long-Term Ownership Summary

• The timing belt is not negotiable. If you are unsure whether the belt has been replaced, schedule the service immediately. One owner noted that a snapped belt can cost $2,500-$4,000 in engine damage, while preventive replacement costs about $800 .
• Use Acura-specified fluids. The 2004 RL requires specific fluids for the transmission (Honda ATF-Z1/DW-1), power steering (Honda PS fluid – not ATF), and coolant (Honda Type 2 blue) .
• Premium fuel is required for optimal performance. Using regular fuel may cause engine knock and reduced performance.
• Maintain your own records. Keep a detailed log of all services (date, mileage, work performed, parts used). This is essential for tracking maintenance history, especially for critical items like the timing belt, given the age of the vehicle .
• Owner manual available. The official 2004 Acura RL Owner's Manual (part number 31SZ3682) is still available from Helm Inc. for $50.00 .
• Factory service manual. A comprehensive 1,954-page factory service manual is available covering all systems of the 1996-2004 RL, including detailed maintenance procedures, wiring diagrams, and repair instructions .