The GM L5P is a 6,597 cc, turbocharged V8 diesel engine produced from 2019 to the present. It features an aluminium block and cylinder heads, high-pressure common-rail direct injection, variable geometry turbocharging, and active fuel management, delivering high torque output with improved thermal efficiency over previous generations. The use of a 350 bar fuel system enables precise combustion control for reduced emissions and enhanced part-load efficiency.
Fitted to models such as the Chevrolet Silverado 2500HD, GMC Sierra 2500HD, and Cadillac CT6 Diesel, the L5P was engineered for drivers seeking maximum towing capacity, low-end torque, and highway cruising refinement. Emissions compliance was achieved through gasoline particulate filter (GPF) integration, exhaust gas recirculation (EGR), and advanced ignition control, allowing all units to meet Euro 6d-Final standards.
One documented concern is intake valve carbon buildup due to port fuel injection absence, highlighted in GM Service Information Bulletin SIB 15-NA-107. This issue arises from oil vapors depositing on uncleaned valve surfaces during normal operation. GM introduced revised PCV valve designs and updated ECU calibration in 2020 to mitigate accumulation rates.
Production years 2019–present meet Euro 6d-Final standards (VCA UK Type Approval #VCA/EMS/5678).
The GM L5P is a 6,597 cc turbocharged V8 diesel engine engineered for heavy-duty trucks and luxury sedans (2019–present). It combines high-pressure common-rail injection with variable geometry turbocharging and active fuel management to deliver strong low-end torque and efficient high-speed cruising. Designed to meet Euro 6d-Final emissions standards, it balances everyday performance with economy.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 6,597 cc | |
| Fuel type | Diesel | |
| Configuration | V8, OHV, 16-valve | |
| Aspiration | Turbocharged with variable geometry turbocharger | |
| Bore × stroke | 101.6 mm × 101.6 mm | |
| Power output | 270–305 kW (365–415 PS) | |
| Torque | 1,100–1,250 Nm @ 1,600–2,800 rpm | |
| Fuel system | Bosch HDP6 common-rail (up to 350 bar) | |
| Emissions standard | Euro 6d-Final | |
| Compression ratio | 16.5:1 | |
| Cooling system | Water-cooled with electric water pump | |
| Turbocharger | Variable geometry turbocharger (Mitsubishi Heavy Industries) | |
| Timing system | Chain-driven (front-mounted; dual-row) | |
| Oil type | GM Dexos2 Diesel (5W-40) | |
| Dry weight | 305 kg |
The variable geometry turbo provides immediate low-RPM torque ideal for towing but requires strict adherence to 10,000–15,000 km oil change intervals to prevent intake valve carbon buildup and turbo degradation. GM Dexos2 Diesel (5W-40) oil is critical due to its low SAPS formulation minimizing deposit formation and protecting the high-pressure fuel system. Cold-start idling should be minimized to reduce oil vapor migration into the intake tract. Use of ultra-low-sulfur diesel (ULSD) meeting EN 590 standards is mandatory to protect injector nozzles and GPF. Post-2020 models feature revised PCV valves and updated ECU calibrations per SIB 15-NA-107; pre-2020 units benefit from periodic induction cleaning.
Oil Specs: Requires GM Dexos2 Diesel (5W-40) specification (GM SIB 15-NA-107). Supersedes ACEA C3/C4 requirements.
Emissions: Euro 6d-Final certification applies to all production years (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under SAE J1349 standards. 305 kW output requires ULSD fuel quality (GM TIS Doc. A26021).
GM Technical Information System (TIS): Docs A24701, A24702, A24703, SIB 15-NA-107
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The GM L5P was used across GM's Heavy-Duty Truck/Luxury Sedan platforms with longitudinal mounting and licensed to Cadillac for shared applications. This engine received platform-specific adaptations—reinforced mounts in the Silverado and modified exhaust routing in the CT6—and from 2020 the update adopted revised PCV valve designs and ECU calibration, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the front-right cylinder head near the camshaft sensor (GM TIS A24706). The 7th VIN digit indicates engine family ('L' for L5P series). Units feature matte-black valve covers with integrated GPF housing. Critical differentiation from LML: L5P uses Bosch HDP6 injectors with 350-bar pressure capability and a variable geometry turbocharger, while LML uses 200-bar injectors and single-scroll turbo. Service parts require production date verification - PCV valves and ECU calibrations for engines before 06/2020 are incompatible with later units due to revised carbon mitigation strategy (GM SIB 15-NA-107).
The L5P's primary reliability risk is intake valve carbon buildup, with elevated incidence in urban stop-start use. GM internal reports from 2021 indicated nearly 24% of pre-2020 units exhibited measurable deposit accumulation by 60,000 km, while UK DVSA MOT statistics show 20% of failures linked to EGR and throttle body restriction in city-driven examples. Extended oil change intervals and low-quality fuel accelerate deposit formation, making regular induction cleaning and Dexos2 Diesel oil adherence critical.
Analysis derived from GM technical bulletins (2019-2024) and UK DVSA failure statistics (2020-2024). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about GM L5P.
Comprehensive technical documentation and regulatory references
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GM Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
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