The popular YouTube channel Engineering Explained is famous for taking complicated engineering concepts, mostly automotive-related, and clearly explaining them to the layman. One of the channel’s latest videos takes a deep dive into the high-profile recall of GM’s 6.2L V8 L87, which affects nearly 600,000 full-size trucks and SUVs in the U.S. alone.
The channel’s host, Jason Fenske, opens the video by explaining the recall, which we’ve covered here thoroughly. The problem involves manufacturing flaws that may lead to rod-bearing damage caused by sediment on the connecting rods and in the crankshaft oil galleries, as well as issues related to the crankshaft specs and finish. When engines have this problem, it leads to loss of propulsion, sometimes requiring an engine replacement.
Fenske goes on to explain that the recall calls for affected units to have their oil replaced with high-viscosity 0W-40 Mobil 1 Supercar oil rather than the 0W-20 oil originally specified upon passing an inspection. Then, he uses his automotive engineering expertise to explain why using a different oil viscosity is supposed to prevent the engine failure issue. 
It’s all about an engineering concept called the Stribeck curve. The Stribeck curve is a way of measuring proper lubrication by charting the friction coefficient on the Y axis and the Hersey number on the X axis. There are three distinct regions on the curve: boundary lubrication (high-friction, metal-on-metal contact), mixed lubrication (some, but incomplete separation between metal parts), and hydrodynamic lubrication (metal parts are completely separated by a layer of oil. Naturally, reducing metal contact decreases friction, making the Stribeck curve go down in the mixed lubrication phase.
The Hersey number measured on the X-axis is a formula that measures lubricant viscosity multiplied by sliding speed divided by load pressure. GM’s goal in using a thicker oil in the L87 engine is an effort to increase the Hersey number so the engine spends more time in the hydrodynamic lubrication phase of the Stribeck curve.
Fenske further explains why GM is making the switch from 0W-20 to 0W-40. Generally speaking, it’s inadvisable to increase the first number or decrease the second number in an engine oil’s viscosity, because it introduces the engine to a viscosity it isn’t designed for. However, increasing the second number isn’t as risky since the whole operating range of 0W-40 oil is within the operating range of 0W-20 oil.
It’s worth watching the whole video if you own one of the affected vehicles and are wondering about the new oil recommendation. The gist is that using thicker oil in the L87 is expected to optimize the engine’s lubrication and prevent catastrophic failure.
Comments
Good information. In a future study, the author may wish to opine as to why the L87 in GM’s pickups and large, frame SUVs is (or formerly, was) recommended for 0W-20 and the virtually identical LT-1 in the 2014-19 Corvette Stingray & Gran Sport and 2016-24 Camaro SS,1LE and LT-1 models is recommended for 0W-40. And tell us why a tracked LT-1 suffers any more or less than a pickup towing a large boat or two axle camper. With heat buildup being the obvious major concern, does an LT-1 tracked at high RPMs suffer more than the L-87 truck/SUV towing say 12,000 pounds? BTW, to date, the Corvettes and Camaros mentioned here have not been recalled. Perhaps the reason the LT-1 in the C7 Corvette and Gen 6 Camaro fare better is because performance car owners change their oil much more frequently. GM even went so far to recommend exactly that to Camaro 1LE owners who track their cars and Z-51 equipped C6 Corvettes who do the same. Of note, the LT-1 in the Corvette Gran Sport & Camaro 1LE models include engine oil coolers and the Silverado/Sierra 1500s quipped with the Tow Group option do as well.
Part of it might be oil duty cycle as well. Most multi weight oil use a base (the first number) and then use friction additives to maintain their viscosity as they get hot (2nd number) when it comes to towing diesels, your common choices are 10w30/15w45 or even 5w45. Most 5w45’s see a duty cycle of 5-7000miles. Before the friction modifiers break down and the oil is too thin. 15w45 hold well, and does give the most protection, so lots of people use it, but 10w30 is the most stable and you can see a truck go 10-15000 miles on 10w30 and it’s still holding up. A truck will doesn’t run a track, so it’s oil only will get as hot as a Corvettes when merging with a trailer or climbing a mountain, which is a 1 minute duty cycle, and not as long as a track car, but on the flip side is expected to go longer between oil changes.
And generally you see the less you have to do to the oil the stabler it is. In theory a full synthetic strait 20 or strait 30 with no modifiers to break down and ample zinc might be capable of 30,000 or more miles on a single change, but it’s largely impractical as it would hurt start up protection and you would need to change out filter 2-3 times on the same oil.
That said, they used to run engines on strait 10, strait 20 mineral oil with no zinc added and rebuild the engines every 500 hours. 😬 I’m not complaining about today’s engines one bit.
Thanks for all the education info Steve. I could go on further about the duty cycles, and what it does to the oil in the form of various contaminations and a main reason for more frequent oil changes but I think that we’ve covered enough on it(the oil topic) for now.
I agree, this is good information. However the engineer failed to explain how a higher viscosity oil would repair the out of spec finish on the Crankshaft journals, or clean up the machining debris left in the rods, and or crankshaft.
Obviously, thicker oil to protect softer surface, and filter remove the junk. I’ve seen engine bearings run for a long time after passing a shard. I also call bull on the shavings, as that’s the same BS Toyota said, but that’s such an elementary thing that it smells more like Toyota is playing a “let’s blame a couple guys on the floor instead of admitting we royally screwed up the design.” This to me seems like a bearing chemistry/finishing issue. Older engines used softer babbit bearings and ran a long time with 10w30/5w30/SAE30, so a 0w40 which has a similar curve would coddle similar bearings very well, but still provide great start up protection for the smaller oil passages.
What about the comment to an earlier article about the increased viscosity leading to decreased mpg?
Remember all the armchair engineers’ opinions in other articles about this issue? You know, the comments without data, which is what opinion is. And how GM was doing everything wrong about this issue. Don’t expect to find them here, because data ! And if they do show up, it’ll be opinion.
A class action suit should be filed against GM by the federal government itself to replace these vehicles, not just the engines. These vehicles should be removed by GM to have these engines replaced and resold at a discount. The unsuspecting buyers should not be punished or inconvenienced in any way for a major flaw.
Two issues: Bad crankshafts made in Mexico and thin oil. The oil was for sure used to make EPA targets for GM’s volume cash cows.
It is as simple as that yet youtube experts are trying to overcomplicate things to sound smart and get subs.
You don’t sound smart and should not get thumbs up.
Appears to me that this is simply GM trying to skate out of fixing their mistake in building these engines with a defect in the bearings, and recommending the wrong oil to try and make the MPG a higher number. If I owned one of these that they claim now changing to higher vis will solve the problem my first stop after said oil change would be a Ford, Toyota or VW dealer to get rid of the problem, and I would expect at least a $10,000 hit on resale value because of GM monumental screw up! ote I drive now and always have GM cars and trucks. Maybe not any longer!
Even though the engine now gets a 150,000 mile warranty???? Your going to a Toyota dealership after their engine debacle and buying a truck 50% less warranty just because they’re being proactive on a potential issue on the most reliable-longest lasting vehicle line in modern history?
That’s fine! Lots of interested buyers will be out looking for your 6.2! It’s your money, feel free to spend it how you want!
What is described in the video is a good bit snake oil. Mostly just a fast talker.
What has STILL not been addressed is the valve lifter failure and GM’s failure to address that problem.
It’s called, attrition, just like the eight speed trannys.
An old trick…put thicker oil in to cover up a bad motor..They’re just trying to get them past warranty coverage
Dude is an idiot he has the wrong oil. The correct oil to use is Mobil 1 Supercar 0W-40 with Dexos. GM does not recommend Mobil 1 European Car Formula 0W-40.
Recently Dexos approved.
From the Mobil1 site:
Mobil 1 ESP Formula 0W-40 carries the dexos®2 approval specified for General Motors vehicles.
There are several Dexos oils. Dexos2 covers European emission spec vehicles.
Dexos1 US gasoline specs. DexosD small GM diesels. DexosR is racing oil.
Mobil 1 Super Car is DexosR racing oil. This is more then just increasing the viscosity.
GM is requiring racing oil in these engines now!
Gm need to recall the 5.3 and 8 speed transmission, 2018 to present year!
What I’m curious about is the fact they claim the issue stops with 2024. I don’t believe they’ve solved anything, and are just saying 2025’s are okay to keep sales going. It is VERY disappointing to spend 100K on a vehicle with such a major issue that they “supposedly” have no fix for (according to my recall).
the issue was found in june 2024, hence it didn’t exist after that. So why recall them? They found the issue and fixed it. No different than you having a water leak in your house and fixing it. And than still saying water is leaking from same spot, when it clearly is not.
I been wanting a new Truck ,Suv with the 6.2 but I’ll be getting a L8T 6.6 like the GMC 2500 HD AT4X AEV, Well I believe that something is causing the malfunction, thicker oil isn’t the Problem, when an engine fails and is still sealed so no parts can escape, everything should still remain inside the block, So where are the parts that caused the failure? They don’t disappear. I believe that they were Never installed to begin with, Smells like Incompetence or Sabotage ,I Think the DOJ AND FBI NEEDS TO BE INVOVLED IN FINDING THE TRUTH.
YouTube channel (I Do Cars) just tore down a 6.2 that was supposed to be included in the recall.
There wasn’t anything missing. The Rod End Bearings were to tighten on the crank shaft. Causes by the rough surfaces, as in not polished to a smooth surface. They got so hot the bearings welded them selves to the crankshaft.
It’s possible that there wasn’t really a rough surface, it’s possible that the bearing shells were too thick causing no clearance for oil. It would be cool to be able to test one of these engines with Plastigauge before it seized up and see just how tight the tolerance between the bearing and crank was.
Because if you think of this, if there was enough space for the oil it should have polished its self. Isn’t that why they want you to take it easy on a new engine, to allow the metal surfaces to seat together.
Another thing that makes me think this is an oil viscosity issue……. The I Do Cars 6.2 had (I believe) 90 thousand miles on it!! Why so long to seize up and fail. By then it should have been in the clear…..
Food for thought ?
Why aren’t 6.2ltr engines in Australia included, they are after all American engines,I have one in my 2011 HSV Grange ( google it ) and it’s still a GM motor!!!
Problem years are 2022-2024. Holden commodore isn’t included.
If a thin oil gave a bit better milage, why do other countries recommend 5w-30
I don’t think he is looking at this from a combined perspective.
Thin oil plus thin transmission fluid and running everything hotter gives much better milage at the cost of more wear on the vehicle……
Why do Harley and Victory use heavy oil? Because thin oil doesn’t protect a hot running motor.
I agree that 0-40 is being recommended to keep metal parts separated. Especially rough surfaces. Then take into account how hot new vehicles run compared to a few years ago.
I guess the proof would be in two vehicles towing on hot days for most of there life then check for wear. Or let’s see if there is any high milage 6.2 out there that have run 0-20 all there life. If I had an engine that called for 0-20 I would still run 5-30. Just makes more sense.
‘the whole operating range of 0W-40 oil is within the operating range of 0W-20 oil’ is an incorrect statement. it’s exactly the opposite. higher weight oil has never fixed a mechanical problem, and never will. this is not a fix, this is GM finding a compromise procedure to kick the problem down the road. GM knows how many vehicles will crash, or become unservicable, and be put out of service before the engine fails. it’s a percentage game, if they can extend the failure time by months. or years – they win – its cheaper. if they can lower the failure percentage from the published 3% (which I believe is laughably low) by a fraction of a percent or a full percent – they win – it’s cheaper. GM doesn’t sell cars – they count beans.
What is up with car manufacturers as of late? GM and there lifter failures had me scared away from there V8s. And even there second design is a disaster. Then they screwed up with the 6.2 and don’t want to replace all the engines. Then there is the fuel pump issues with the pump control module, Transmission issues, it goes on and on. Time Mary came to work and did something about all the issues. Or step down and let someone else run the company. I have no faith in GM anymore.
Then we have Ford with there cam fazer failures, wet belt disasters in the 1.0, 2.3, 2.7, and even the 5.0. And even while they were having wet belt failures they decided it would be a good idea to ad the wet belt to the 2.7 and 5.0……. Both engines were top notch before this decision. WTF…….
Why would any manufacturer make such a stupid decision??
And Toyota screws up and has engine failures. And there has been many other complaints of quality issues with there other vehicles too. Is this about trying to save a buck and it backfires and ends up costing a fortune to rectify.
I would like to see massive penalties for wasting energy building things such as replacement engines. This is causing more of a wast of resources than most of these so called milage improvement designs are saving.
This is old news and incorrect at that. New bulletin has us look at date stamp on block. If after a certain date no fix needed. If before replace engine. Still going to be using the 0w20
wrong. if build date of engine is before week 183 of 2024, all that means is it needs checked. If you have the computer code of P0016, than you get replacement engine. If not, than you get 0 w 40 oil and new oil cap. Just because you might fall within build date does not automatically mean you get new engine.
Bandaid until is out of warranty
The oil viscosity change helps the situation where the originally recommended 0-20 isn’t thick enough to provide the proper oil film between the moving parts (crank journal and rod bearing). That could be due to undersized surface area between them or too hard of bearing material or a surface finish problem or they just screwed up thinking they could get away with super thin oil. But this oil viscosity change does nothing to address trash left in the oil passages of the crank shaft. That trash either clogs the passage and starves the bearing for oil or it scores the bearing and crank surfaces, both shortens the bearing life. Once it gets past the bearing and into the pan, the oil filter should catch it so it doesn’t go through again. If it’s machining trash that’s left inside the engine on the outside of the rods, crank or block surfaces, it will most likely be washed down into the pan and filtered out, not ideal but not too hard on the engine’s rotating parts. Unless the trash is on the cylinder walls then that’s a whole other issue of premature cylinder wall and ring wear but not an oil issue. I’m a mechanical engineer and have been a mechanic on the side for many years and I commend the guy who did the oil film calculations and graphics, I remember learning about that way back in college and it’s important for the people who originally design the engines and spec the lubricants but really the failures are common sense. If the bearing to journal contact area is too small or there’s too much clearance the heavier oil will help but it’s really just a bandaid on the real problem. This is another reason to always change oil on a new vehicle within the first 1000 miles and use a high quality oil and filter.
My replacement (Jan 2025) in my 2023 High Country had an oil change 0-20!
Runs like a champ but listen a lot closer now. Dealer invoice just under 10k US$.
This is just a bandaid for the problem, if Mary Barra would compromise on production cost, maybe they could use better materials and build some quality vehicles.
Thing started going south when they changed the composition of the TCC
(Torque Converter Clutch) friction material, again, to cut production cost they omitted the Kevlar that was in the TCC lining, this was what gave the TCC duribillity after 2018 8L90E transmission torque converters were failing by the thousands. 😡