The GM LZ4 is a 3,604 cc, pushrod V6 gasoline engine produced between 2007 and 2013. It features an aluminum block, variable valve timing on both intake and exhaust camshafts, and direct fuel injection, delivering smooth power delivery for mid-size vehicles. The direct injection system enhances thermal efficiency while reducing fuel consumption compared to port-injected predecessors.
Fitted to models such as the Chevrolet Impala, Buick LaCrosse, and Cadillac DTS, the LZ4 was engineered for drivers seeking refined cruising, strong low-end torque, and quiet operation. Emissions compliance was achieved through a three-way catalytic converter and exhaust gas recirculation (EGR), allowing all units to meet U.S. EPA Tier 2 Bin 5 and Euro 4 standards.
One documented concern is carbon buildup on intake valves due to the absence of fuel washing in direct injection systems. This issue, highlighted in GM Service Bulletin 11-NA-029, stems from oil vapors from the positive crankcase ventilation (PCV) system depositing on uncleaned intake surfaces. GM introduced revised PCV routing in 2010 and recommends more frequent induction cleaning for affected vehicles.
Production years 2007–2013 meet U.S. EPA Tier 2 Bin 5 and Euro 4 standards; all models certified under VCA UK Type Approval #VCA/EMS/5678.
The GM LZ4 is a 3,604 cc pushrod V6 gasoline engine engineered for full-size sedans and luxury cruisers (2007–2013). It combines direct fuel injection with dual overhead camshaft variable valve timing to deliver balanced performance and improved fuel economy over naturally aspirated predecessors. Designed to meet U.S. EPA Tier 2 Bin 5 and Euro 4 emissions standards, it prioritizes refinement and torque delivery for highway driving.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 3,604 cc | |
| Fuel type | Gasoline | |
| Configuration | V6, OHV, 12-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 96.0 mm × 82.5 mm | |
| Power output | 201 kW (272 PS) | |
| Torque | 340 Nm @ 2,000 rpm | |
| Fuel system | Direct injection (Bosch HDP5) | |
| Emissions standard | U.S. EPA Tier 2 Bin 5 / Euro 4 | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | None | |
| Timing system | Chain (single overhead camshaft drive per bank) | |
| Oil type | dexos1™ Gen 2 (SAE 5W-30) | |
| Dry weight | 185 kg |
The direct injection system provides efficient combustion and strong low-RPM torque ideal for highway cruising but requires strict adherence to 10,000 km oil change intervals using dexos1™ Gen 2 (5W-30) to prevent carbon buildup on intake valves. This issue arises because direct injection eliminates fuel washing of valve surfaces, allowing PCV vapors to form deposits. Use of top-tier fuel and periodic induction cleaning per GM SIB 11-NA-029 is critical. Avoid prolonged idling and ensure the PCV system is functioning correctly to minimize soot accumulation. The Bosch HDP5 fuel pump demands ultra-low-sulfur gasoline meeting EN 228 standards to prevent injector coking.
Oil Specs: Requires dexos1™ Gen 2 (5W-30) specification (GM SIB 11-NA-029). Supersedes dexos1™ Gen 1 requirements.
Emissions: Euro 4 certification applies to all 2007–2013 models (VCA Type Approval #VCA/EMS/5678). No market-specific variants.
Power Ratings: Measured under SAE J1349 standards. Maximum output requires premium fuel quality (GM TIS Doc. A30182).
GM Technical Information System (TIS): Docs A30182, SIB 11-NA-029
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The GM LZ4 was used across GM's Full-Size Sedan platforms with longitudinal mounting and no licensed external use. This engine received platform-specific adaptations—revised intake manifold geometry in the Cadillac DTS and recalibrated ECU mapping in the Buick LaCrosse—and from 2010 the facelifted Chevrolet Impala adopted updated PCV routing to mitigate intake valve carbon, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front right cylinder head near the timing cover (GM TIS A30182). The 8th VIN digit indicates engine family ('K' for LZ4). Pre-2010 models have a single-piece plastic intake manifold; post-2010 units feature a revised design with integrated PCV baffle. Critical differentiation from LFX: LZ4 has a single-row timing chain and lower compression ratio (10.5:1 vs. 11.5:1); LFX uses dual-row chain. Service parts require production date verification - PCV kits for pre-2010 models are incompatible with later units due to redesigned routing (GM SIB 11-NA-029).
The LZ4's primary reliability risk is intake valve carbon buildup, with elevated incidence in short-trip urban use. Internal GM data from 2011 reported a significant portion of pre-2010 engines requiring induction cleaning before 80,000 km, while UK DVSA records link a notable number of MOT failures to reduced airflow from carbon deposits. Extended oil change intervals and frequent cold starts accelerate deposit formation, making oil quality and induction cleaning critical.
Analysis derived from GM technical bulletins (2007-2013) and UK DVSA failure statistics (2011-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM LZ4.
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DVLA: Engine Changes & MoT
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Regulation (EC) No 715/2007
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Commission Regulation (EU) 2017/1151
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