3.0L Duramax LZ0/LM2, 6.2L L87 V8 & 10-Speed Transmission Specs
Comprehensive engineering specifications, fluid capacities, torque curves, and transmission valve body diagnostics for GMC AT4 and AT4X powertrains.
3.0L Duramax LZ0 Diesel vs 6.2L L87 V8 Powertrain Architecture
GMC AT4 powertrain options feature the 3.0L Duramax LZ0 inline-6 turbo-diesel (305 hp, 495 lb-ft requiring 7.0 qts Dexos D 0W-20) and the 6.2L EcoTec3 L87 V8 (420 hp, 460 lb-ft requiring 8.0 qts Dexos 1 Gen 3 0W-20), both mated to the Hydra-Matic 10L80 10-speed automatic transmission.
Selecting between the 3.0L Duramax LZ0 turbo-diesel and the naturally aspirated 6.2L EcoTec3 L87 V8 on the GMC Sierra 1500 AT4 dictates driveline dynamics, off-road low-speed crawl control, and payload margins. As detailed on our master GMC AT4 specifications hub, both powerplants deliver exceptional torque output, but their delivery profiles differ dramatically. The inline-6 Duramax achieves its peak 495 lb-ft of torque at an ultra-low 1,500 RPM, allowing drivers to feather the throttle over steep rocky obstacles without wheel slip. Conversely, the 6.2L L87 gas V8 generates 420 horsepower, reaching peak torque at 4,100 RPM for aggressive highway passing.
Interactive Vector Engine Pinout & Drivetrain Specifications Matrix
| Engine Option | Displacement & Fuel | Power Output | Peak Torque | Oil Capacity & Spec | Transmission |
|---|---|---|---|---|---|
| 3.0L Duramax Inline-6 Turbo-Diesel (LZ0) | 3.0 Liters (182 cu in) · Ultra-Low Sulfur Diesel (B20 Approved) | 305 HP @ 3,750 RPM | 495 lb-ft @ 2,750 RPM | 7 Qts · 0W-20 (Dexos D Certified (Strictly GM dexosD mandatory)) | Hydra-Matic 10L80 10-Speed Automatic |
| 6.2L EcoTec3 V8 with Dynamic Fuel Management (L87) | 6.2 Liters (376 cu in) · 91+ Premium Unleaded Gasoline | 420 HP @ 5,600 RPM | 460 lb-ft @ 4,100 RPM | 8 Qts · 0W-20 (Dexos 1 Gen 3 Certified) | Hydra-Matic 10L80 10-Speed Automatic |
| 5.3L EcoTec3 V8 with Dynamic Fuel Management (L84) | 5.3 Liters (325 cu in) · 87 Regular Unleaded Gasoline | 355 HP @ 5,600 RPM | 383 lb-ft @ 4,100 RPM | 8 Qts · 0W-20 (Dexos 1 Gen 3 Certified) | Hydra-Matic 10L80 10-Speed Automatic |
| 6.6L Duramax V8 Turbo-Diesel (L5P) | 6.6 Liters (403 cu in) · Ultra-Low Sulfur Diesel | 470 HP @ 2,800 RPM | 975 lb-ft @ 1,600 RPM | 10 Qts · 15W-40 (or 5W-40 Synthetic for cold climates) (Dexos D / API CK-4 Heavy Duty Diesel) | Allison 10-Speed Heavy Duty Automatic |
Factory Fluid Capacities, Dexos Oil Viscosities & Filter Part Numbers
Maintaining strict adherence to General Motors factory fluid specifications prevents catastrophic timing chain failure, AFM DFM Lifters failure, and Transmission Valve Body scoring. The 3.0L Duramax LZ0 requires an ACDelco PF66 Oil Filter paired with Dexos D 0W-20, whereas the 6.2L EcoTec3 L87 utilizes the PF64 Oil Filter with Dexos 1 Gen 3 0W-20. For heavy-duty applications, the Sierra 2500HD AT4 utilizes the commercial Allison 10-Speed transmission. When modifying tire dimensions, vehicle speed sensor signals alter transmission shift timing; recalibrate using our tire diameter speedometer correction calculator.
Variable Geometry Turbocharger (VGT)
The 3.0L Duramax LZ0 utilizes an electronically controlled variable vane turbo generating up to 34.8 psi of boost pressure.
10L80 10-Speed Transmission Valve Body Diagnostics & Shift Solenoid Specs
The Hydra-Matic 10L80 10-Speed Transmission utilizes an ultra-wide 7.39:1 overall ratio spread. The first gear ratio of 4.70:1 paired with the AT4's 3.23:1 or 3.73:1 rear axle ratio generates immense mechanical torque multiplication at the drive wheels. When towing heavy travel trailers or equipment haulers, verify total vehicle capacity via our engine towing ratings and hitch limits workbench.
Total Wheel Torque Multiplication Formula
Variable Definition & Units
495 lb-ft (671 Nm)
4.70:1
2.72:1
3.23:1
18,375 lb-ft (24,913 Nm)
Frequently Answered Questions About AT4 Powertrain & Duramax Maintenance
01What is the difference between the 3.0L Duramax LM2 and the newer LZ0 engine in GMC AT4 trucks?
The 3.0L Duramax LZ0 (introduced for the 2023 production generation) succeeded the earlier LM2. Key improvements include upgraded steel pistons with a revised combustion bowl, tuned fuel injectors, a retuned variable-geometry turbocharger (VGT), improved cylinder head cooling jackets, and upgraded rear-mounted wet oil pump belt materials. These revisions boosted output from 277 hp / 460 lb-ft on the LM2 to 305 hp / 495 lb-ft on the LZ0.
02Can I use standard Dexos 1 motor oil in the 3.0L Duramax LZ0 turbo-diesel?
No. The 3.0L Duramax LZ0 strictly requires motor oil certified to the GM Dexos D standard (0W-20 viscosity). Standard Dexos 1 Gen 3 oil is formulated for gasoline engines and lacks the specialized additive packages required to withstand diesel soot loading and protect the rear oil pump drive belt running submerged in engine oil.
03What causes harsh 1st-to-2nd gear shift clunks on the GM Hydra-Matic 10L80 transmission?
Harsh low-speed shift flares or clunks on 10L80 10-speed transmissions are frequently caused by torque converter clutch (TCC) slip, contaminated valve body separator plates, or outdated transmission control module (TCM) shift adaptives. General Motors issued TSB 20-NA-167 recommending a transmission adaptive learn relearn procedure and inspection of shift solenoid line pressure.
04How often should transmission fluid be changed on a GMC AT4 driven off-road or towing frequently?
While the GM factory owner's manual lists 45,000 miles for severe service, ASE certified technicians strongly recommend servicing the Dexron ULV transmission fluid and internal sump filter every 30,000 miles if the truck is regularly used for off-road rock crawling or towing trailers above 7,000 lbs.
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