NHTSA opens preliminary probe into more than 870,000 GM vehicles

[WalleyeMikeIII]

LOL, first you're daugheer is probably wearing the pants in the relationship if her fiancé is driving a Prius.
Second, yeah,, you do realize that Prius engine doesn't make anywhere near the torque of a 6.2 right. So its not trying to push the thin out out from between the bearings near as hard as the big V8.
Could the thin oil work in the bg V8, yeap it sure could, if (and only if) you fed enough volume at sufficient pressure to the bearings, but the oil pump is something else they cut a bit on the 6.2. So the options are either replace the oil pump or run a thicker oil.
...

LOL, their relationshp is fine...they are both super frugal, so he willingly took the hand me down from his mother...

Yes, I know HP in the 2.0 Honda 4 cyl is 200, and in the prius is smaller than that...

The poster said "he would not run 0W20 in a modern engine" and my point is you can run it reliably in a modern engine..based on these examples.

BTW, the HP/CYL of the Honda is actually on par w/ the 6.2, and higher than the 5.3....torque per cylinder is a similar story...so if you break it down to force between rod and crank...the story may not actually be all that different...right?

We are kind of stuck in a situation though...while 5W30 Dexos might actually help us...if we blow the thing in the powertrain warranty...and they come back and say we didn't run the recommended oil...do we get a warranty replace on the engine? It is a pickle.

 

[blanchard7684]

Sommerfeld relation to eccentricity ratio would strongly suggest that the 6.2 needs a higher viscosity.

The RPM/load ratio (Omega/W) would support moving the eccentricity ratio away from 1.0 which is technical contact between journal and bearing.

This relation is standard relation for bearing design. It is solved iteratively to find the eccentricity ratio required to generate a hydrodynamic film of sufficient strength to balance the applied load from the journal (a reaction force)

You want to avoid being on the extremes of this curve.

For high load and low rpm operation, adding viscosity (the "u" term) will keep film strength such that the eccentricity ratio won't be near the .7, .8, .9 range.

The 5.3 can get away with the 0w20 because it operates at higher RPM for the same load. The hydrodynamic reaction force generated at this rpm is sufficient to balance the load and doesn't need added eccentricity to generate this reaction force. Thus 0w20 can work here for a 5.3.

Even for a 5.3 it is probably sketchy when you throw in longer OCI and fuel dilution.

The 3.5 ecoboost runs a 5w30. That is a heavily loaded bearing at full load. Not sure if the ecoboost is running 1200-1500 rpm at highway speeds.

All this is assuming there isn't an issue with jaw fits, bearing crush, and journal taper issues on the crank.

 

[KMeloney]

100% YES, absolutely.

The short block and rotating assembly is identical, part number for part number, between the base Corvette 6.2 and the truck 6.2 ( camshaft has a different grind though). Guess what weight oil GM specs for that ,,, spoiler alert ,, it isn't 0W20.

Mobil 1 even came out with a GM dexos approved oil just for this, and its available at most regular autoparts stores.

Mobil 1 Supercar Advanced Full Synthetic 0W-40 Motor Oil 1 Quart | AutoZone

Get more out of the road. Mobil 1 Supercar 0W-40 is an advanced full synthetic motor oil specifically designed for high performance North American sports cars to provide exceptional cleaning power and wear protection, and deliver outstanding overall performance. Hold onto your steering wheel...

www.autozone.com

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What are you running in your '23? (And you've got a 6.2 also, right?)

 

[KMeloney]

I think the 6.2l is a perfect storm of a number of issues. There were clearly some part problems, but these should have been flushed out a while ago. The lifter bore issue, assume this was resolved.

A while ago as in WHEN? I've got a '23, which is specifically referenced in the Customer Satisfaction engine-replacement memo. If I'm sitting on bad parts, then it is what it is. But if I can stave off a failure with a change in oil type, then I'll do it.

 

[jerry455]

If you are under the warranty, I would run what is recommended. Mine is out of warraty so I am running 0W30 in my 6.2. I may use 5W30 in the summe.

 

[Antonm]

What are you running in your '23? (And you've got a 6.2 also, right?)

Yes is a 6.2, currently I'm running the dexos rated 0W40 Mobil 1 oil (figured I'd give it a shot to see what the oil sample looks like), but I've tried the 0W40 euro spec Mobil1 and the 5W30 truck & SUV Mobil 1 (right now the 5W30 truck & suv mobil 1 is looking pretty good though)

While I like Mobil 1 obviously, there are plenty of other oils out there that are just as good, oil brand really isn't all that important. All of the premium synthetics are on Par with each other, run whatever name brand you like.

But here are two oil samples , one at 6K total miles on the engine (3K miles on the oil) with 0w40 euro spec mobil 1 and another with 12K total miles on the engine (6K on the oil) with 5W30 truck and SUV mobil1. I don't have any other sample results on this computer (my work computer), but the others look similar as far as wear particle count goes . And as long as its under 5ppm combined wear particles per 1K miles driven, I call that good.

6K miles on engine (8 ppm wear particles/ 1K miles, little high, but the engine is still breaking in at only 6k total miles)

12K miles on engine (3.8 ppm wear particles/ 1k miles, which is good IMHO)

...

 

[jfoj]

So here is the deal with running something other than 0W20 engine oil. If there is a failure, the dealer is not going to perform an oil analysis. Even if they did, the higher viscosity would show up only if the oil is not typically fuel diluted. But the engine would not be failing for a slightly higher viscosity oil anyway. Plus these engines have a pretty bad track record anyway so nobody is really going to question a failure.

@KMeloney, my sources tell me there were some bad bearings during COVID 2021, some may have made it into the earier 2022 MY builds, they likely have 2021 date codes on the rear of the bearing shells. For 2023 this was I beleive for the Oversize Lifter Bore problem. I would have your dealer run your VIN. Also get the truck up on ramps or a lift and get a picture of the engine production tag on the rear driver side cylinder head. The engine will have a Julian date in part of the label and you can find out exactly which day and year the engine was built. What is the build month and year of your truck? Chances are the engine may be 2-6 weeks younger than your truck.

There are a lot of things owners can do to hopefully prolong the life of these engines. I think a lot of what is happening has to do more with fuel dilution, oil consumption causing the engines to be run low on oil, extended oil changes (I would not go beyond 50% of the OLM) and not running premium fuel.

After a lot more research and thinking on the overall oil subject and actually speaking with some well known and well regarded people in the lubrication industry, I think the best oil option is probably the Pennzoil Ultra Platinum synthetic. This is due to its higher levels of Molybdenum which is a very good engine oil additive to reduce friction and holds up better under high pressures and high temperature conditions. While this oil is not Dexos licensed, it is partially due to GM requiring the oil vendor to divulge the oil chemistry and ingrediants as well as paying a licensing fee to GM. So many higher end or speciality oils that have an 'edge' over the competition tend to not want to have some of their products licensed to protect their products.

Each their own, I will be running some oil analysis on the Pennzoil Ultra Platinum and as long as the calcium levels are in line with the Dexos oils I am good with it.

If I can run a better oil, higher viscosity that will protect the engine, why would I not want to do this? My goal is to not have the engine sieze if I can do anything to protect it. Pretty simple approach IMHO. I am sure others will disagree.

 

[Jesse729]

This is an interesting discussion about the oil viscosity. I could have lack of knowledge here but I am wondering why the discussion is not gravitating more towards the variable displacement oil pump? While it might be complex, could a solution be to defeat or disable the variable displacement have have the pump running at a higher volume?

 

[Antonm]

I am wondering why the discussion is not gravitating more towards the variable displacement oil pump?

Because we’re lazy and don’t want to mess with the oil pump or its control system when putting in a different weight oil during an oil change will solve the issue is mostly the reason the discussion isn’t going more towards oil pump modifications.
…

 

[seatown]

I just want to say…

I’ve been here on the couch since 930pm last night. It’s currently 135am.

You could outline the basics for a good article on motors and fluids and mechanicals, and modern manufacturing QA, etc from this thread.

It’s been an interesting back and fourth.

Many guys on here with detailed experience. And even some complex math… but shit it’s been good learning.

Also there’s the politics of it all.. **** Covid

The oil is interesting to me. Clearly oil is critical. If I get a 5.3L I’ll help be a test unit.

The gas mixing is interesting to. Is that just a built in with a V8 or a GM V8? How precise is it in there?

Tying into the AFM/DFM… I have a 08yukon with 250k that uses some sort of that technology. What is different?

It does seem like there is underlying faulty parts woven in a more complex engine design… KISS

But Good info thanks. I think as long as the rig I am looking to buy is CPO with good warranty left I’m going to jump on board in a 5.3L. One final question, when buying am I responsible to look at the vin and check those notice articles?

 

[Stbentoak]

If 0W-20 is so bad, why aren't 3.0 Duramax's failing too? Have read many reports of them exceeding 150K miles with no engine/oil related issues, including regular towing....

 

[blanchard7684]

If 0W-20 is so bad, why aren't 3.0 Duramax's failing too? Have read many reports of them exceeding 150K miles with no engine/oil related issues, including regular towing....

This is a good question.

Different bearing design is likely to the case. The 3.0 makes 90% of its torque below 1250 rpm. Static loading is sensitive to bearing width by a cubic factor.

The ecoboost has high torque output at low rpm, but it specs 5w30...

 

[jfoj]

The 3.0l Duramax is a different animal, it should be designed for Low RPM/High Torque operation. Torque pec for the LM2 is 460 ft/lbs Torque at 1500 RPM, the LZ0 is 495 fl/lbs Torque at 2750 RPM.

The L87 6.2l is designed as a higher RPM motor. Torque Spec is 460 ft/lbs @ 4100 RPM. However the L87 6.2l rarely runs above 2000 RPM in my experience. On the surface this looks like a non issue, however, with the 10 speed transmission and the Torque the 6.2l puts out at lower RPM, the engine is often operating at 90+ plus actual torque at RPM ranges between 1200-1700 in these larger trucks based on how they are configured. This puts an extreme load on the engine components, oil film and even sets up a perfect storm for Low Speed Pre Ignition (LSPI). I am working on gathering some data on how the 6.2l behaves on the highway pulling gradual grades. What I am seeing is a bit disturbing with engine Torque loads over 50% for a good portion of the drives and peaks up to 95% at 1600 RPM. This clearly shows the 6.2l is behaving more like a Diesel than a typical gas engine in these trucks. Base on preliminary info on the 5.3l engines, they do not generate near the amount of low end Torque and the trucks are confirgured to downshift and the engines tend to operate at higher RPM's when pulling inclines and grades.

The L87 would be much happier operating at 2500+ most of the time, but due to fuel ecomony requirements, this is not in the cards for this engine in these 6000 bricks. I have not seen the levels of failures in the smaller vehicles using the same basic 6.2l configuration.

Again, the basic gasoline V8 design has typicaly been for higher RPM operation than Diesels. Diesels tend to have design considerations to support very Low RPM/High Torque operation, probably larger/wider connection rods, larger bearing journals, larger and wider bearings and so forth. Diesels also are not impacted by LSPI as they are not spark ignition engines, so this alone could be a big difference in the heavier vehicles.

Based on some of my conversations with oil analysis staff, they are telling me 0W20 is not an ideal oil for the Duramax. I assume this is based on lab testing results, the Duramax engines do not appear to be failing catasphopically like the 6.2l, they may be showing elevated signs of bearing wear that may only show up in much higher mileage situations? I also assume fuel dilution of the engine oil is also a consideration for the Duramax as well which would reduce the oil viscosity at the miles accumulate on the engine oil. I did not get into a detailed conversation about the Duramax as I am mainly focused on the 6.2l engines. Just passing on what I was told.

 

[Doubeleive]

Omg. Lol. Not the gubment!

ya because there is no such thing as CAFE or the EPA, and there is no consideration to mandate 0-20 by 2027 or that is was previously considered earlier but was pushed back and.....
funny thing many other owners manuals in countries outside the USA "may" recommend 0-20 but also state that other viscosities are also acceptable given the intended use and clearly state that 0-20 is more or less for economy.
also it is a pretty well known fact that when engines wear and when those tolerances are no longer within spec a higher grade oil can help prevent oil consumption
gee I wonder why that happens.......
high mileage engine oil? omg lol

 

[Scarey]

If low rpm’s are part of the problem would sport mode or tow/haul help?

 

[jfoj]

Put the transmission in L7!! 1.00 gear ratio, but mileage will suffer!

 

[seatown]

there is clearly electrical in this DFM system, but is is apart of the failures?

 

[jfoj]

I really did not want to put this specific graph out due to it only being for a period of 2 minutes driving somewhat just outside of town with a few peaks.I am trying to find time and the place to obtain more data. This will hopefully give an idea about the engine loading that is occuring. But look at the RPM, no more than 1500 RPM for the peak calculated engine load at or over 80%. This means the transmission was probably not in 10th gear at these speeds.

My Yukon pretty much runs around 1200 RPM at 55 MPH and 1400 RPM at 65 MPH and unless the grade is faily steep, the transmission rarely downshifts. The engine Torque usually just pushes the vehicle along with very little RPM change when hitting inclines. So the engine is getting heavily loaded at lower RPMs on a regular and sometimes sustained basis.

I have not had time to hit the road and find the right conditions to generate a longer graph with more sustained engine loading, I have watched it happen on many occations in real time, did not have the data logging set up to caputure it at that time. I have been rather shocked/surprised at some of the engine loading I have been seeing and for how long it is occuring while cruising on the highway.

I am sure there will be some comments, yes this graph is for 6.2l not the 3.0l Diesel!!

 

[Stbentoak]

This is a good question.

Different bearing design is likely to the case. The 3.0 makes 90% of its torque below 1250 rpm. Static loading is sensitive to bearing width by a cubic factor.

The ecoboost has high torque output at low rpm, but it specs 5w30...

I'll be the first to agree that 0W 20 oil is thin, super thin..... a lot thinner than I would really like to run. But I'm not willing to take any chances on warranty. I'll error on the side of changing it a little more often than necessary. See where that takes us.....

 

[Antonm]

If 0W-20 is so bad, why aren't 3.0 Duramax's failing too? Have read many reports of them exceeding 150K miles with no engine/oil related issues, including regular towing....

Because the 3.0 has a different oil pump ( it’s even belt driven) that puts out more volume and pressure than the 6.2.

With a higher volume and higher pressure oil pump, the 6.2 could get away with running thin oil too.

But considering we change oil anyway on a regular basis, its a whole hell of a lot easier to put in thicker oil than re-design the oil pump.
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