BREAKING: GM is officially recalling the L87

[jfoj]

Gm is extending the warranty on motors that just get an oil change to 0W40. 10yrs or 150,000 miles https://gmauthority.com/blog/2025/0...od-engines-to-get-extended-warranty-coverage/

This entire 6.2l debacle is moving at warp speed. It will be interesting to see if GM backs out of large scale engine replacement because the GM N252494002 says very different things than the "Oil Change" Recall.

Maybe someone let out a draft document that was under consideration, but once the Genie is out of the bottle, hard to put it back in.

 

[jfoj]

Note that the Reddit post says to refill the new engine (Line 3) with 0W20......

N252494002 Page 3

That's because the "new" engines built after July 1, 2024 are supposed to be the "good" engines. But I also think there are some underlying CAFE, EPA issues at play here. Just changing from 0W20 to 0W40 will SLIGHTLY impact fuel economy and therefore the vehicle no longer meets the approved CAFE/EPA documents originally submitted and the EPA Fuel Economy numbers will likely be lower.

 

[LegalBrief]

Think about this, the bulk of the older engines have already failed, the 2024 will have a few failures, they will inspect the engines and replace a few more. Then over the next decade they will deal with anymore failures, that eases the impact to production and the service departments. Not all engines will fail, they know which parts went where… very reasonable solution.

 

[Scarey]

Not sure which it is, replace all engines in this range or inspect and replace as needed?

 

[vcode]

That's because the "new" engines built after July 1, 2024 are supposed to be the "good" engines. But I also think there are some underlying CAFE, EPA issues at play here. Just changing from 0W20 to 0W40 will SLIGHTLY impact fuel economy and therefore the vehicle no longer meets the approved CAFE/EPA documents originally submitted and the EPA Fuel Economy numbers will likely be lower.

Exactly, which clearly indicates that mfg defects are causing the problem, not oil.

 

[jfoj]

I suspect the spin doctors will be out sometime next week to try to explain all this away.

 

[vcode]

Unless GM starts filling new truck and SUV 6.2's from the factory with 0W40, oil is not the culprit here.....

 

[LegalBrief]

Unless GM starts filling new truck and SUV 6.2's from the factory with 0W40, oil is not the culprit here.....

The issue is defective parts and an oil port, by changing the oil viscosity the oil port is addressed.

The 2025 has a redesigned oil port and different parts (or perhaps parts supplier).

 

[Stbentoak]

Not to mention have you seen the price of 0W-40 supercar oil? There are like 3-4 Mobil variations of 0W-40.. Super car is like 25 bucks a qt. Plus the "You need to change it more frequently crowd" ? Talk about expensive.....What if you go like 3 years on this 0-40 stuff before a failure?

Maybe I'm wrong and "Supercar" variant wasn't the prescription....

 

[blanchard7684]

This guy is really scientific and detailed. Good video.

Cliff notes

0w20 won't make your engine blow up/seize or malfunction if you continue to use it and keep it changed often...aka don't get lazy or cute with long oil change intervals.
0w20 and all other ultra low viscosity oils are designed to improve fuel consumption in a very specific drive cycle designated by SAE (for EPA).
Downside is reduced safety factor in oil film thickness.
Upside is statistically validated improvement in fuel economy.

0w40 is good because it has exceptional HTHS capability. 0w40 has 3.5-3.6 HTHS viscosity (cSt)
HTHS is a worst case scenario for what a bearing "sees".
2.3 -2.6 is minimum HTHS by SAE...0w20 operates right at 2.6 cSt. Right at the minimum.
Therefore not much safety factor.

Stribeck curve shows the tribological regimes for lubrication: boundary, mixed, and hydrodynamic

All "0" oils will have the same boundary lubrication. And the mixed lubrication will be similar. The separation happens with hydrodynamic lubrication.

The stribeck factor of speed x viscosity/load is from Sommerfeld formula. In other words, Sommerfeld picks up where Stribeck leaves off.

My take from the video and current recall information:

0W40 is recommended because GM has found a defect in manufacturing that is upsetting the bearing clearances where by 0w20 can't carry the load effectively. This is likely a reduced clearance scenario: crank taper, rod concentricity, bearing crush issue from rod caps being slightly off spec.

This creates a hot spot such that 0w20 film thickness drops to a point that looks like a huge increase in eccentricity ratio in Sommerfeld.

To counteract this, a higher viscosity oil is used.

The new replacement engines and the 2025's are spec'd with 0w20.