GMC Sierra 1500
6.2L V8, 420 hp, same Gen V architecture as the 5.3 but deeper exhaust note and noticeably more shove. 2021-2024: manufacturing left metal shavings in 597,000 engines — GM's fix was switching to 0W-40 oil. NHTSA opened an investigation into post-recall failures. Same DFM lifter risk as the 5.3. Pre-2021 or confirmed post-recall units with documented oil changes are the buy.
6.2 Denali T1XX — peak GM truck, recall shadow
This is the truck GM wants to sell: 420 hp, Denali interior, MultiPro tailgate, magnetic ride. Then 597,000 L87 engines got recalled for metal shavings. NHTSA investigating if the oil-swap fix works. A post-recall Denali with clean oil analysis is a magnificent truck — if the engine holds.
Engine Weaknesses 4
Manufacturing debris (metal shavings) in engine destroys bearings. 2021-2024 L87. Free engine replacement, 6-8 week wait. NHTSA investigating post-recall failures.
Same lifter issue as 5.3L — cylinder deactivation wears lifters.
Symptoms: Ticking/knocking, misfires, rough running
Piston rings let oil past — 0.5-1 quart per 2,000 miles in severe cases. Also affects 2019-2020 L87 not covered by the machining debris recall. NHTSA investigating these cases separately.
Symptoms: Blue smoke, dropping oil level, fouled spark plugs, positive oil consumption test
Timing chain and guides wear at high mileage — same issue as the 5.3L V8.
Symptoms: Cold start rattle, P0008/P0016 OBD codes
Vehicle Weaknesses 6
Corroded sub-frame ground strap causes simultaneous power steering and brake assist failures. Wiring harness chafing on ECM causes limp mode. Same platform issue as Silverado T1XX.
10L80 transmission develops harsh shifts and shudder. Multiple class actions filed. GM fluid flush (Mobil 1 LV ATF HP) helps temporarily. Severe cases require torque converter or complete transmission replacement under warranty extension.
Factory wax coating peels off frames within months of purchase. Visible surface rust on new trucks. GM issued service bulletin acknowledging the issue. Same problem across all T1XX platform trucks (Sierra, Silverado).
Shift to Park warning appears with transmission already in Park. Key gets stuck, battery drains overnight. Caused by worn shift cable bushing or electronic gear selector contact issue.
Sierra-exclusive MultiPro 6-way tailgate has actuator latch failures (micro-switch sends false signal), hinge binding, and step deployment issues. Load stop does not lock open. Exposed mechanisms vulnerable to dirt, ice, and salt. PIT5895A TSB for 2022 refresh disable function. Warranty covers most failures but repeat visits common.
Power running boards fail to deploy, retract immediately, or deploy randomly when parked. Motor failure on one side common from ~60k miles. GM service update: reprogram K4 Assist Step Control Module (RPO B3L/BRS). Physical motor failure: $190 OEM part, $850 dealer installed.