10/10/2026
GM has recalled nearly 600,000 trucks and SUVs in the US over the 6.2L L87, and most of the talk around it has stayed pretty surface level. Dave at Dave’s Auto Center got his hands on one of the warranty engines that failed GM’s PicoScope test and tore it down on camera.
His theory is that it takes two things happening together. Waviness in the crankshaft journal surface, working against the variable displacement oil pump. He’s been going through it with metrologist Mark Malburg and tribologist Lake Speed Jr., and the surface trace they show has the crank finish rising and dipping in microns across roughly 20mm of journal.
He explains it like a wave at the beach. Every peak has a trough behind it, and every trough is a spot where the oil film pressure collapses. Do that a few dozen times across a bearing surface and you eventually get metal touching metal.
The rod bearings back it up. Polished bands where the coating is gone and the bearing has been kissing the crank, worse on the rod side than the cap side, which is exactly where the combustion load lives.
Then there’s the part he wasn’t looking for. A bent pushrod on number four led to a lifter that had rotated 180 degrees in its guide with an edge sharp enough to cut you. He figures the debris off that is what took out the number one main bearing, because the rest of the mains looked fine.
Worth noting the oil in this thing was clean. No sludge, no neglect. It got there anyway.
What he wants to build is an option for owners who pass the Pico test and get told their engine is fine. Reprogram the variable displacement pump to hold higher oil pressure at idle and light load. That means pulling the ECM and trans controller and sending them out to be unlocked, since Global B isn’t something you plug a handheld into. He says he’s running dyno testing and oil analysis before he puts his name on it. Finally an answer to GM engines going to poo.
