The 2006 Acura RL is Honda's flagship sedan with a 3.5L V6 and SH-AWD system. While built to a high standard, it suffers from catastrophic engine failures due to a factory defect in the cylinder bore plating and a transmission that can fail expensively even with proper maintenance.
Cylinder Bore Plating Failure (Nikasil-style FRM Liner Degradation)
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: Excessive oil consumption (1+ quart per 1,000 miles), Blue smoke on startup or acceleration, Rough idle, misfires, and loss of compression, Metal debris visible in oil during changes
Fix: Complete engine rebuild or replacement required. Honda used a thin fiber-reinforced metal (FRM) coating on cylinder walls that can delaminate, causing piston ring wear and bore scoring. Rebuild involves boring out the FRM and installing sleeves, or replacing with a known-good engine. 18-25 hours labor for rebuild, 12-16 hours for used engine swap.
Estimated cost: $4,500-8,500
Automatic Transmission Failure (5-Speed)
Occasional · high severityTypical onset: 90,000-140,000 mi
Symptoms: Harsh shifting, especially 2nd to 3rd gear, Slipping or flaring between gears under acceleration, Transmission overheating, burnt ATF smell, Check engine light with P0730, P0740, P0780 codes
Fix: The 5-speed automatic can suffer clutch pack and torque converter failure. Early fluid changes help but don't prevent it entirely. Requires rebuild or replacement. Rebuild: 14-18 hours; used transmission swap: 10-12 hours. Be aware the external oil cooler can leak internally and contaminate ATF.
Estimated cost: $3,200-5,500
Transmission External Oil Cooler Contamination
Common · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Milky or contaminated transmission fluid, Sudden transmission slipping after coolant system work, Transmission overheating warnings, Pink or red residue in coolant reservoir
Fix: The external ATF cooler integrated into the radiator can fail internally, allowing coolant and ATF to mix. This destroys the transmission quickly. Requires cooler replacement, complete ATF flush (often multiple cycles), and sometimes full transmission rebuild if contamination was severe. Preventive replacement recommended. Cooler replacement alone: 3-4 hours.
Estimated cost: $600-1,200 (preventive); $3,500-6,000 (if transmission damaged)
SH-AWD Rear Differential Fluid Contamination
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Whining or grinding noise from rear end during turns, Vibration at highway speeds, SH-AWD warning light illuminated, Clunking when engaging/disengaging AWD
Fix: The Super Handling AWD rear differential and transfer case are sensitive to old or incorrect fluid. Many shops use wrong spec fluid causing accelerated wear. Requires Honda DPS-F fluid only. If noise present, rear differential may need replacement or rebuild. Fluid change: 1.5 hours. Rear diff rebuild/replace: 8-12 hours.
Estimated cost: $180-300 (fluid service); $2,500-4,200 (rebuild/replacement)
Power Steering High-Pressure Hose Leaks
Common · low severityTypical onset: 80,000-130,000 mi
Symptoms: Power steering fluid leaking near firewall or pump, Groaning noise when turning at low speeds, Low fluid level requiring frequent top-offs, Burning smell from fluid contacting exhaust
Fix: The high-pressure PS hose degrades and develops pinhole leaks or cracks at crimped fittings. This was subject to a recall but many weren't caught before hose failed naturally. Replacement requires removing engine cover and working around tight firewall area. 2-3 hours labor. Use OEM hose only; aftermarket rarely fits correctly.
Estimated cost: $350-600
Takata Airbag Inflator Recall Compliance
Common · high severitySymptoms: Recall notice received but not yet completed, SRS light may or may not be illuminated, No symptoms until catastrophic failure during deployment
Fix: Multiple Takata airbag recalls affect driver and passenger inflators. These can explode violently, sending metal shrapnel into cabin. VERIFY recall completion before purchase—many RLs still have unfixed inflators due to parts shortages in past years. Acura dealers replace for free. 1-2 hours per inflator.
Estimated cost: $0 (recall repair at dealer)
Hard pass unless you're getting it extremely cheap (<$3,000) and have a plan for the inevitable engine and/or transmission rebuild—these are money pits despite the luxury and SH-AWD appeal.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.