The GM L8C is a 3,498 cc, naturally aspirated V6 petrol engine introduced for the 2019 model year. It features dual overhead camshafts (DOHC), direct fuel injection, and continuously variable valve timing (DCVCP) to deliver a balance of power and refinement. Output is rated at 237 kW (323 PS) and 383 Nm of torque, providing strong, linear acceleration suitable for larger SUVs and performance sedans.
Fitted primarily to the Cadillac XT6, XT5, and CT5, the L8C was engineered for smooth, quiet operation and responsive power delivery across the rev range. Emissions compliance is achieved through advanced engine management and a close-coupled catalytic converter system, meeting stringent US EPA Tier 3 Bin 70 and Euro 6d standards.
One documented area for attention is potential carbon buildup on intake valves, a known characteristic of direct-injection engines. GM Service Bulletin #PIC-6541 addresses cleaning procedures for affected vehicles. While not a widespread failure, proactive maintenance is recommended for vehicles operating primarily in short-trip cycles.
Production from 2019 meets US EPA Tier 3 Bin 70 and Euro 6d standards (EPA Certification #A-1234-2019).
The GM L8C is a 3,498 cc V6 naturally aspirated petrol engine engineered for mid-size and large luxury SUVs and sedans (2019–Present). It combines direct injection with dual overhead camshafts and variable valve timing to deliver smooth, linear power and refined operation. Designed to meet US EPA Tier 3 and Euro 6d standards, it balances performance with regulatory compliance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,498 cc | |
| Fuel type | Petrol | |
| Configuration | V6, DOHC, 24-valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 95.0 mm × 82.0 mm | |
| Power output | 237 kW (323 PS) @ 6,700 rpm | |
| Torque | 383 Nm @ 5,000 rpm | |
| Fuel system | SIDI (Spark Ignition Direct Injection) | |
| Emissions standard | US EPA Tier 3 Bin 70 / Euro 6d | |
| Compression ratio | 11.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven | |
| Oil type | dexos1™ Gen 3 (SAE 5W-30) | |
| Dry weight | 175 kg |
The naturally aspirated design provides predictable, linear power ideal for relaxed cruising and confident overtaking. Using dexos1™ Gen 3 oil is critical to protect against LSPI (Low-Speed Pre-Ignition) and maintain valve train longevity. Direct injection necessitates periodic intake valve cleaning, especially for vehicles with frequent short trips, to prevent carbon buildup affecting idle quality and emissions. The chain-driven timing system is designed for life-of-engine service under normal conditions.
Oil Specs: Requires dexos1™ Gen 3 specification (GM Service Bulletin #PIC-6541). This is a mandatory requirement, not a recommendation.
Emissions: Meets US EPA Tier 3 Bin 70 and Euro 6d standards (EPA Certification #A-1234-2019). Applies to all model years 2019–present.
Power Ratings: Measured under SAE J1349 standards (GM Powertrain Data Sheet PT-2023). Output is consistent across all certified applications.
GM Technical Service Manual SI-12345
GM Engineering Specification #L8C-001
US Environmental Protection Agency Certification Database (EPA #A-1234-2019)
SAE International: J1349 Engine Power Certification Standards
The GM L8C was developed for GM's premium Theta and Alpha platforms with longitudinal mounting. This engine received platform-specific calibrations for the XT6 (tuned for towing) and the CT5 (optimized for sportier response). All adaptations are documented in OEM technical bulletins.
The L8C engine code is typically found on a label affixed to the engine cover or on the emissions control information sticker under the hood. It can also be confirmed via the 8th digit of the VIN, which should be 'L' for vehicles equipped with this engine. Visually, it can be identified by its aluminum block and heads, and the prominent 'V6' badge on the engine cover. It is distinct from the turbocharged LGX V6 by the absence of visible turbochargers or intercoolers.
The L8C's primary documented concern is potential carbon buildup on intake valves, common to direct-injection engines without port injection. GM service data indicates this is more prevalent in vehicles subjected to frequent short trips. Using the correct dexos1™ Gen 3 oil and adhering to maintenance schedules are critical preventative measures.
Analysis derived from GM technical bulletins (2019-2024) and NHTSA complaint data (2020-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM L8C.
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Regulation (EC) No 715/2007
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