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GM 3.0L Duramax I6 Turbo Diesel Reliability Report
An in-depth investigation into the reliability of General Motors' only 6-cylinder turbo diesel engine for GMC and Chevrolet vehicles, covering both LM2 and LZ0 generations.
Executive Summary
General Motors introduced the 3.0L Duramax inline-six turbo diesel engine in 2019 as the company's first and only 6-cylinder diesel option for GMC and Chevrolet light-duty trucks and SUVs. This groundbreaking engine promised exceptional fuel economy, substantial torque, and refined performance.
However, the reliability story is complex. The original LM2 generation (2019-2022) demonstrated generally solid reliability with several manageable issues, while the updated LZ0 generation (2023-present) initially appeared to resolve earlier problems but has been plagued by a serious thrust bearing defect affecting 2025-2026 model years, resulting in catastrophic engine failures at extremely low mileages.
Engine Specifications by Generation
Compare the technical specifications and improvements between LM2 and LZ0 generations
LM2 Generation
2019-2022 Model Years
LM2 Generation
@ 1,500 rpm
Real-world average
Silverado 1500
LZ0 Generation
2023-Present Model Years
LZ0 Generation
@ 2,750 rpm
Real-world average
Silverado 1500
Key Improvements in LZ0 Generation
- City MPG
- Highway MPG
- Horsepower
- Torque (lb-ft)
Critical Issue: 2025-2026 Thrust Bearing Failures
A serious defect affecting 2025-2026 model year LZ0 engines has resulted in catastrophic "grenading" failures at extremely low mileages. GM has issued a Technical Service Bulletin (TSB 25-NA-307) but has not issued a formal recall.
- • 2025-2026 Chevrolet Silverado 1500
- • 2025-2026 GMC Sierra 1500
- • 2025-2026 Chevrolet Tahoe
- • 2025-2026 Chevrolet Suburban
- • 2025-2026 GMC Yukon / Yukon XL
- • Knocking/rattling from bellhousing area
- • Low oil pressure warning light
- • Check engine code P06DD
- • Reduced acceleration warning
- • Complete engine failure
2025 GMC Yukon XL
Engine grenaded while towing, mid-August 2025 build
2025 Tahoe RST
Crankshaft broke loose, dealer's 3rd replacement that month
2025 Yukon Ultimate
Over a month in shop for engine replacement
2025 Denali
Engine and turbo replaced due to thrust bearing failure
Reliability Issues by Generation
Performance & Owner Feedback
- Exceptional fuel economy: Real-world 27-30+ MPG highway vs. 18-20 MPG for gas V8s
- Strong low-end torque: 495 lb-ft @ 2,750 rpm makes towing effortless
- Refined operation: Smooth, quiet, lacks harsh diesel character
- Perfect transmission pairing: 10-speed automatic shifts seamlessly
- Impressive towing: Up to 13,300 lbs capacity in half-ton truck
- 2025-26 thrust bearing failures: Catastrophic at under 10,000 miles
- No recall issued: Owners not proactively notified of defect
- Rear main seal leaks: Even on low-mileage vehicles
- Oil pump belt design: Unusual choice introduces potential failure mode
- Quality control concerns: Multiple issues suggest manufacturing challenges
"I've had the 3.0 LZ0 for a little less than a year and it's by far my favorite - previously having an F-150 with Coyote 5.0, then previously Chevy 5.3s. This 3.0 has more torque than those engines, and it's all low end. When I pull our trailer it pulls with ease where the gas engines would be grunting. I'm running high 20s on each tank. Efficient and powerful low end torque. Having your cake and eating it too so to speak."
— Reddit user, 26,000 miles on LZ0
Recommendations for Prospective Buyers
Used vehicles from these model years with documented maintenance histories may represent reasonable purchases for buyers who understand the known issues.
- ✓ Verify software updates have been applied
- ✓ Check rear main seal for leaks
- ✓ Budget for oil pump belt replacement at 150,000 miles
These model years appear to have avoided the thrust bearing problem and benefit from improvements over the LM2. May represent the best option for buyers seeking a 3.0L Duramax.
RecommendedDO NOT purchase until GM issues a recall and definitively resolves the thrust bearing problem. The risk of catastrophic engine failure at low mileage is too high.
If considering a used example:
- • Verify engine has been inspected for crankshaft end play
- • Confirm measurements fall within specifications
- • Better yet: wait for GM to address the issue
Conclusion
General Motors' 3.0L Duramax inline-six turbo diesel represents an ambitious and technically impressive engine that delivers genuine benefits in fuel economy, torque, and refinement. When functioning properly, it provides an excellent ownership experience that justifies its premium price for the right buyer.
However, the reliability record is deeply concerning, particularly for 2025-2026 model years affected by thrust bearing failures. The lack of a formal recall represents a significant failure in corporate responsibility and has damaged consumer confidence.
For buyers committed to diesel power in a light-duty truck or SUV, the 3.0L Duramax remains the only option in the segment following the discontinuation of competing engines from Ford and Ram. GM must address quality control issues decisively to maintain consumer confidence and justify continued investment in light-duty diesel technology.
Data Sources
This report synthesizes information from CarBuzz, GM Authority, Pickup Truck Talk, Motor Trend, Diesel Power Products, Prosource Diesel, Reddit r/Diesel, Duramax Forum, SilveradoSierra.com, and GM Technical Service Bulletin 25-NA-307.