6.2 L87 (not LT1) discussion

[SS71SS24]

Originally Posted by olrocker

Of course even though I knew mine was built in Tonawanda I still pulled my engine cover off to look lol

Curious as to how you know where your engine was built. After breaking down my V.I.N., it doesn't distinguish which engine plant. Does your passenger side head pad say "T" or "TOR" or some other code?


Right now, I'm a thousand plus miles from my 24 SS vert M6 and just killing time...

[m6-lt1]

Originally Posted by SS71SS24

Curious as to how you know where your engine was built. After breaking down my V.I.N., it doesn't distinguish which engine plant. Does your passenger side head pad say "T" or "TOR" or some other code?


Right now, I'm a thousand plus miles from my 24 SS vert M6 and just killing time...

LT1’s were all built at the Tonawanda plant aside from a small batch of engines assigned to manual transmission cars for MY2020-mid 2023.

[Capricio]

Does having an engine built/assembled at a particular location (tonawanda) imply the cranks/bearings were machined from a different mill than an engine assembled at a different location (bowling green/spring hill)?

I assumed all the cranks/bearings same from a sole source, regardless of point of assembly. Still unclear whether or not LT1s got the exact same bearings as L87 but people say the part numbers are all the same, so... I dunno.

The defective crankshafts and connecting rod bearings for the 6.2L L87 V8 engines, which prompted a massive recall of 2021-2024 GM trucks and SUVs, were sourced from a supplier located in Mexico.

Crankshaft Supplier: The problematic crankshafts were manufactured by Questum Macimex in Mexico.

Connecting Rod Supplier: The connecting rods were provided by American Axle & Manufacturing.

Root Cause: The issues stem from machining defects, specifically improper surface finishes or incorrect dimensions on the crankshafts and sediment in the oil galleries.

Engine Assembly Locations: While the parts were sourced from these suppliers, the L87 engines themselves were built at GM's Tonawanda, New York; Spring Hill, Tennessee; and St. Catharines, Ontario plants. Some reports specifically point to the St. Catharines plant for assembling the defective units.

There is no information in the recall documents that definitively states Questum Macimex supplied the LT1 crankshafts, or that LT1 engines are part of the current L87 recall.

[olrocker]

Originally Posted by SS71SS24

Curious as to how you know where your engine was built. After breaking down my V.I.N., it doesn't distinguish which engine plant. Does your passenger side head pad say "T" or "TOR" or some other code?


Right now, I'm a thousand plus miles from my 24 SS vert M6 and just killing time...

Since I spec ordered my car and bought it brand new with 2 miles on it I have the window sticker which tells you engine and trans build locations.

[SS71SS24]

Originally Posted by olrocker

Since I spec ordered my car and bought it brand new with 2 miles on it I have the window sticker which tells you engine and trans build locations.

I spec ordered mine as well and have looked over the window sticker. Mind I ask where the engine plant is located on the sticker? Thanks!

[SS71SS24]

Hi olrocker :
Just found what you said. Engine US, Trans US. I feel better already! Not a Canadian sourced 6.2L !

[SS71SS24]

Just discovered that the redline for the L87 6.2L in a 2026 Silverado is 6000RPM. We know the redline for the LT-1 6.2L in the Gen 6 Camaro is 6500RPM. Hmmm.
Speaking only from an historical perspective, a lower redline in" similar" small block Chevys was always done for a particular reason.
Case in point: In 1972 the Corvette, for the first time, could be ordered with a solid lifter engine and air. The fabled LT-1 of that era had a 6,500 RPM redline however when equipped with air, RPM redline dropped to 5,500 RPM. Back then it was because the A/C belt would fly off at high revs.
Could the L-87 6.2L have a mechanical limitation as compared to the LT-1 6.2L?

[m6-lt1]

Originally Posted by SS71SS24

Could the L-87 6.2L have a mechanical limitation as compared to the LT-1 6.2L?

Nope. Now I will let you know the L87 has more collapsible lifters but that’s not why it revs lower. The L86 had the same amount of collapsible lifters as the LT1 but that also only revved to 6k like the L87.

The reason the 86/87 rev lower than the LT1 is simply because the intake manifold is designed to make more torque at a lower RPM than the LT1. It simply does not have to rev to make power which is what you want for a truck engine.

The main (and possibly only) differences between the L86/87 engines versus the LT1 are the oil pan, oil pump (I think), accessory routing, intake and exhaust manifolds. As mentioned before the L87 has more collapsible lifters than the L86/LT1. They are pretty much identical internally (heads, cam, bottom end).

[bishopts]

Originally Posted by m6-lt1

Nope. Now I will let you know the L87 has more collapsible lifters but that’s not why it revs lower. The L86 had the same amount of collapsible lifters as the LT1 but that also only revved to 6k like the L87.

The reason the 86/87 rev lower than the LT1 is simply because the intake manifold is designed to make more torque at a lower RPM than the LT1. It simply does not have to rev to make power which is what you want for a truck engine.

The main (and possibly only) differences between the L86/87 engines versus the LT1 are the oil pan, oil pump (I think), accessory routing, intake and exhaust manifolds. As mentioned before the L87 has more collapsible lifters than the L86/LT1. They are pretty much identical internally (heads, cam, bottom end).

This is true. The longer runner intake on the truck is the main mechanical difference. The truck engine can rev to 6500 but it's losing power there so it doesn't make sense to.
The heads are definitely the same. I replaced one of mine and the part number was the same for the truck.

[lbls1]

Originally Posted by olrocker

I didn’t know where to put this thread since while it’s a motor similar to 6th gen Camaros it’s not the exact same. So if mods think it needs to be moved go right ahead.

I’m really trying to follow the situation with the L87 6.2. I want to buy a new Tahoe with it but I am NOT touching them until GM has certifiably fixed the failure issues for CERTAIN with a documented engineering repair/redesign.

NOT a simple change in recommended oil viscosity. They’re still failing.

So can those of you with much more knowledge about the situation please post everything you know and where things are in the lawsuit?

Thanks.

I have been buying General Motors products for at least 40 years (counting my first car). Of the new cars from GM, all but one of my cars have been reliable with no engine or related failures.

When I decided to buy my recent new car, I considered everything (including the 6.2 L failure stores). I decided that it was worth the risk based on GM's past reliability and performance of the LS1 based engines. Additionally, every automaker have had their share of issues and failures (Toyota and Ford included). The last point was that the GM Twins were the only ones that were offering everything that I wanted from a new v8 automobile. It was based on these three substantial factors that I decided to take the plunge.

This current new GM automobile isn't necessarily treated the same as my previous cars. Immediately after I took delivery on my Silverado, I put it on the road for a 2400 mile round trip. The truck performed flawlessly. At today's date the truck continues to perform flawlessly without even the slightest sign of trouble (not even a dead battery). I also have no trouble in believing that this pickup truck will continue to perform flawlessly indefinitely.

This is my experience with GM cars to this date. GM is well endowed when it comes to technology and build quality. Where I feel that they have lacked is judgment of the current market and some missteps. If GM intends to remain as a main factor in the automotive market then they should be able to analyze their problems and put in corrective measures.

[olrocker]

They just changed the recommended oil again

https://gmauthority.com/blog/2026/02...l-formula/amp/

[m6-lt1]

Originally Posted by olrocker

They just changed the recommended oil again

https://gmauthority.com/blog/2026/02...l-formula/amp/

If I am recalling correctly this isn’t necessarily a “change” and I’m 99% sure it means we can use it in LT1’s as well. There is an oil thread somewhere on these forums where someone figured out the Mobile one FS 0w-40 now meets dexos R specs. That means it can be put into the LT1 (and any other newer GM tech engine calling for Dexos R and 40w).

This recommendation is simply to save money, but not necessarily in a bad way as the oil meets the specs and folks buying L87’s aren’t driving them on a racetrack (ie the reason to use Supercar as it may sheer down less bad versus FS).

[olrocker]

Originally Posted by m6-lt1

If I am recalling correctly this isn’t necessarily a “change” and I’m 99% sure it means we can use it in LT1’s as well. There is an oil thread somewhere on these forums where someone figured out the Mobile one FS 0w-40 now meets dexos R specs. That means it can be put into the LT1 (and any other newer GM tech engine calling for Dexos R and 40w).

This recommendation is simply to save money, but not necessarily in a bad way as the oil meets the specs and folks buying L87’s aren’t driving them on a racetrack (ie the reason to use Supercar as it may sheer down less bad versus FS).

The point is GM is just changing oils instead of actually fixing the engines.

[Martinjlm]

Originally Posted by olrocker

The point is GM is just changing oils instead of actually fixing the engines.

I think it's "and", not "instead of". If they are correct that the issues are the result of a manufacturing process that was out of control and they've addressed that process, there's nothing that needs to be redesigned or re-engineered in the product. Just build them the way they're supposed to be built and pay more attention to the manufacturing processes.