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You bought a premium truck expecting years of reliable service. Instead, drivers are dealing with sudden mechanical issues, confusing maintenance requirements, and repair bills that sting. These aren’t isolated incidents, but widespread problems affecting several owners. Let’s check out a few.

Catastrophic Bearing Failures

The L87’s most devastating issue strikes without warning. GM’s NHTSA investigation reveals bearing failures that can cause engine seizure or connecting rod breaching. These failures occur shockingly early, sometimes just 4 miles from the dealership, with the defect typically manifesting around 1,147 miles.

Dynamic Fuel Management Lifter Collapse

DFM technology promised better fuel economy but delivered headaches instead. Valve lifter failures plague L87 engines with fewer than 10,000 miles, particularly those built between September 2020 and March 2021. The problem often returns after repairs, with owners experiencing sequential bank failures. 

Crankshaft Manufacturing Defects

Poor manufacturing quality control created internal engine damage that’s impossible to ignore. The problem stems from sediment in crankshaft oil galleries, as well as out-of-specification crankshaft issues. GM’s own analysis of 28,000 field complaints found 14,332 cases involving complete loss of propulsion.

Oil Viscosity 

GM’s oil fix gives rise to new problems for drivers. The company switched from 0W-20 to thicker 0W-40 oil for affected engines to address lubrication issues. However, thicker oil increases internal friction and reduces fuel efficiency. Lawsuits claim folks will buy hundreds of extra gallons annually. 

Oversized Lifter Bores

Some 2023 L87 engines left the factory with a fatal flaw—oversized lifter bores that doom the engine from day one. There is only one solution: a complete engine replacement. Apparently, affected vehicles in dealer inventory can’t be sold until engines are swapped. 

Loss Of Propulsion

When L87 engines fail, they don’t just sputter but die completely. Catastrophic failures occur through engine seizures or connecting rod fractures, resulting in a total loss of power. These dangerous breakdowns occur at highway speeds, posing a serious risk of crashes. 

Delayed Diagnosis Codes

The engine’s problems hide until it’s too late. Dealers check for P0016 diagnostic codes, but engines often pass inspection without triggering warnings. Most individuals report zero advance notice before catastrophic failure. However, some lucky drivers notice subtle signs like unusual knocking or check engine lights. 

Widespread Recall Impact

GM let this issue spiral out of control before taking action. The company allowed L87 troubles to reach 34 times the size of Toyota’s V6 recall, with 28,102 complaints versus Toyota’s 824. The massive recall affected around 877,710 models from 2021–2024. 

Extended Engine Replacement Wait Times

Getting a replacement engine feels like waiting for a miracle. Owners face a backlog of 4 to 8 months for new engines rather than rebuilds. Besides, some important parts, such as lifters and head gaskets, remain backordered despite GM’s Tonawanda plant working overtime. 

Premium Fuel Requirements

The L87 demands expensive fuel but gives confusing guidance. Manuals and gas door labels recommend 91 octane, although some documentation suggests 93 octane, while claiming that 87 is acceptable. Similar engines experience pre-ignition concerns with lower octane fuel, suggesting L87 risks.