And at the end of the day, I believe all these 6.2l L87 failures are not due to one single issue, I believe it is a multitude of problems that add up and under the correct conditions can be catastrophic.
Some of the possible problems, each is probably only a partial contributor
1. Improper crankshaft final machining and polishing. This was supposedly corrected for build from July 2024 forward but we are still seeing failures, maybe not at the original rate for the pre July 2024 engine builds, but there are still failures for 2025-2026 builds and replacement engines manufactured after July 2024.
2. Oil viscosity issues. 0W20 will work, but gives NO safety margin for shear, fuel dilution and the high constant torque loading of this engine in these 6000 lb vehicles.
3. Dropping rod bearing Teflon coating, the main bearings are still coated but the rod bearings are not. I believe the reason the main bearings are currently coated it to protect from lack of oil film for all the addition starting with ASS enabled. If GM would have continued the use of rod bearing coating I would gather the 6.2l failure rate would be 50% or less of the current numbers. Penny wise, pound foolish!
4. Improper cleaning of engine blocks, cranks, rods after machining. This is an easy way for the manufacturers to blame the problem not on the design or choices that were make during the design but blame the assembly process or human assembly process.
5. DFM taking oil volume and pressure away from the end of the oiling path. GM should have done what Ford did in the 1960's with their race engines, feed the main/rod bearings with oil first and the cam, lifters and rocker arms last. The DFM system is far more active and all lifters are capable of collapsing then compared to the prior version of the AFM. Double or more oil requirement to operate the DFM when compared to AFM on the same basic engine.
6. Oil pump & pressure control. The 5.3l L84 does not utilized the 2 stage electrically controlled oil pressure feature. The 5.3l L84 operates at slightly higher oil pressure than the 6.2l L87. This is a big problem with the 6.2l L87 IMHO.
7. Oil filter design. Again, not sure why GM has the 13 larger oil inlet holes on the OE PF63 oil filter and so many of the aftermarket filters have fewer and smaller inlet holes. This along with smaller micro filter media that could be partially restrictive could be a contributor to oil starvation.
8. The 6.2l L87 TCM (Transmission Control Module) is programmed very differently than the 5.3l L84 TCM for the same vehicle. The 6.2l L87 seems to hold off downshifting and forces the engine to load up far more than the 5.3l L84. This is likely due to GM utilizing the extra torque from the 6.2l L87 and trying to get better fuel economy on the highway. But this puts a lot of strain on the engine bearings because the engine is constantly spiking over 75% loading under 2000 RPM.
I am sure there are other items I did not touch on, but it seems GM designed a perfect storm with the L87 6.2l and again, maybe there is no single weak point, but add a few of these items above under the right conditions and oil film breaks down and heat is generated for a short term before you are then waiting on the side of the road for a tow truck.
