OCI, not when but why?

[customboss]

2 hours ago, Grumpy Bear said:

• [Quotes from the link]

 

• The higher the κ value, the better the lubrication condition of the bearing and its expected rated life. This must be judged against the possible friction increase because of the higher oil viscosity. 

 

• κ > 4 (i.e. better than full film lubrication) will not further increase the rating of the bearing. However, κ > 4 may be useful in applications where the bearing temperature rise is small and additional lubrication condition reliability is desirable. This would apply, for example, to bearing applications with frequent start-stop running conditions or occasional temperature variations.

So basically what I've been saying. More than you need only hurts economy, not reliability. One of those 'additional lubrication condition reliably" situations is when using cheap VM's. 

 

An additional note: 

 

• EP/AW additives containing sulphur-­phosphorus can reduce bearing life. Generally, SKF recommends testing chemical reactivity of EP/AW for operating temperatures above 80 °C (175 °F).

Not in doses used in PCMO's of any era. 

Is this new to you? It’s not for anyone who ever worked in The industry and made a living at it. Do you just enjoy reading your own posts? I’m happy you just confirmed for yourself what most pros knew 100 years ago. 

[Grumpy Bear]

Know what motor is full of roller bearings, ball bearings and needle bearings? Big ends and mains and rockers. Harley Davidson. Know what the sulfur and phosphorus levels are for those oils? >2200 ppm phos and over 3.5% sulfur. Ever see a Harley with a lube based bearing  corrosion issue? Me either nor anyone else that LOOKED.  

 

Here's a big difference between my long term experience and others anecdotal stories about, "I've done this for decades without issues?" I take my apart at life cycle end. Big difference between measurement and didn't have a issue.

 

Had a fella once that had a motor he thought 'ticky' but running just fine so thought his program solid. Goateed him into a tear down. Wrist pins egg shaped was the source of the noise. Pins dragging the cylinder walls and locks knocked out of it but hey....it was running fine. Yea it was using a quart in under a thou but not smoking so what's the problem? 

 

Whatever.... 

[customboss]

3 hours ago, Grumpy Bear said:

Know what motor is full of roller bearings, ball bearings and needle bearings? Big ends and mains and rockers. Harley Davidson. Know what the sulfur and phosphorus levels are for those oils? >2200 ppm phos and over 3.5% sulfur. Ever see a Harley with a lube based bearing  corrosion issue? Me either nor anyone else that LOOKED.  

 

Here's a big difference between my long term experience and others anecdotal stories about, "I've done this for decades without issues?" I take my apart at life cycle end. Big difference between measurement and didn't have a issue.

 

Had a fella once that had a motor he thought 'ticky' but running just fine so thought his program solid. Goateed him into a tear down. Wrist pins egg shaped was the source of the noise. Pins dragging the cylinder walls and locks knocked out of it but hey....it was running fine. Yea it was using a quart in under a thou but not smoking so what's the problem? 

 

Whatever.... 

[Grumpy Bear]

I forgot in the Harley post above that oil temperatures in the Twin Cam motors when worked can run OVER 300 F sump temperatures without coolers and hence the 20W50 20W60 recommendations. A point worth noting in the phos./sulfur will kill rolling elements in oil temperatures over 175 F arguments. Not even at a hundred over that point at twice the PCMO current specs.  

 

Rode the 'Tail of the Dragon' one year on my 2005 TC88 with a friend and his 2006 TC94 Ultra and a local fella that tagged along for the day. It was over 90 F that day. If you know the road then you know that speeds fast enough to keep an air cooled big twin in check are not possible and kids, we didn't ride it at a leisurely pace. At the end of that run my oil temp was under 200 F. My bike is fitted with the HD high volume oil and scavenger pumps, filled with Red Line 10W40 and running two coolers and a push in oil temp gauge as were all three bikes. Tom, my riding partner finished the ride at around 270 F. His bike on Red Line 20W50 and without coolers. That third fella on a stock TC 88 was 305F. No coolers and running HD black bottle 20W50 made by Citgo at that time. I still own that bike. Tom passed and who knows what happened to the other fella. 

 

On more leisurely rides Tom and I took across the USA at road speeds between 60 and 85 mph Oliver, my TC88, routinely ran air temperature + 90 degrees and in the mountains I would blind one or both coolers to keep the oil over 175 F. Tom was pretty much 225 to 250 F mountain to desert. Why do I tell this experience? (Remember I run two coolers and 10W40)

 

From the SKF link a few posts ago: 

 

[Quote] When a bearing has reached its normal speed and operating temperature, the lubrication condition of the bearing is:

where

κ	Lubrication condition of the bearing, i.e. viscosity ratio
ν	Actual operating viscosity of the oil or the grease base oil [mm2/s]
ν1	Rated viscosity, function of the mean bearing diameter and rotational speed [mm2/s]

The actual operating viscosity, ν, of the lubricant can be determined from the ISO viscosity grade of the oil, or the grease base oil, and the operating temperature of the bearing...[Close Quote]

 

Give that some thought next time you're towing and running 0W20! 

And/Or running 70 in tow mode in other than top gear at Max weight.

 

Hersey is viscosity dependent and viscosity is temperature dependent. 

 

When I first got Pepper it had a 207 F thermostat and the oil heater/cooler in the V-6 models is in the hot tank and is a 5 element stacked plate exchanger that runs counter current. My oil temps ran 220-225 F on normal days of average temperatures and over 235 F at 70 mph on a hot day; 250 F+ ratting her. Something I did  not know until I got my Scan Gauge II. 

 

For most of her life she has run on Red Line HP 5W30 or HP Euro 5W30 whose HTHS viscosity is 3.7 cSt. A hard step up from the DEXOS1Gen2 5W30 call out with a HTHS of 2.9 cSt. And she was fitted with a thermostat of 170 F to lower bulk oil temperatures below what trading that Group III swill for a PAO had already provided. Top line in the graph below the top blue line is the oil temperature vs speed, OEM setup and OEM oil. Green line at the bottom is the current fitment and Red Line Euro 5W30.

 

No one and i mean NO ONE says a word when I drop the oil temperature 25 to 40 degrees but has a cow when I up the viscosity a grade or two. What does that tell you about the understanding of such people? Experts that don't grasp the temperature relationship of the Hersey Equation. No one says a word when I use a 5W30 with a 15W40 HTHS. Again, no understanding. 

 

Or how about the fella's tell me that the saw a huge increase or decrease in hot oil pressure with a grade change. 20 degrees is about one grade and I've added recently another switching to RL HP Euro 5W40 and...nada....a half a needle width on the oil temp. Lack of understanding is killing more equipment that the OEM call outs and these people are the ones I am supposed to take advise from? 

 

 

I don't tell you what I think. I report what I measure. 

Then I do me and let you do you.

 

 

 

Edited August 16, 2025 by Grumpy Bear

[Grumpy Bear]

 

Interesting notes at 10 minutes in on what is considered clean. 

Edited August 16, 2025 by Grumpy Bear

[customboss]

7 hours ago, Grumpy Bear said:

I forgot in the Harley post above that oil temperatures in the Twin Cam motors when worked can run OVER 300 F sump temperatures without coolers and hence the 20W50 20W60 recommendations. A point worth noting in the phos./sulfur will kill rolling elements in oil temperatures over 175 F arguments. Not even at a hundred over that point at twice the PCMO current specs.  

 

Rode the 'Tail of the Dragon' one year on my 2005 TC88 with a friend and his 2006 TC94 Ultra and a local fella that tagged along for the day. It was over 90 F that day. If you know the road then you know that speeds fast enough to keep an air cooled big twin in check are not possible and kids, we didn't ride it at a leisurely pace. At the end of that run my oil temp was under 200 F. My bike is fitted with the HD high volume oil and scavenger pumps, filled with Red Line 10W40 and running two coolers and a push in oil temp gauge as were all three bikes. Tom, my riding partner finished the ride at around 270 F. His bike on Red Line 20W50 and without coolers. That third fella on a stock TC 88 was 305F. No coolers and running HD black bottle 20W50 made by Citgo at that time. I still own that bike. Tom passed and who knows what happened to the other fella. 

 

On more leisurely rides Tom and I took across the USA at road speeds between 60 and 85 mph Oliver, my TC88, routinely ran air temperature + 90 degrees and in the mountains I would blind one or both coolers to keep the oil over 175 F. Tom was pretty much 225 to 250 F mountain to desert. Why do I tell this experience? (Remember I run two coolers and 10W40)

 

From the SKF link a few posts ago: 

 

[Quote] When a bearing has reached its normal speed and operating temperature, the lubrication condition of the bearing is:

where

κ	Lubrication condition of the bearing, i.e. viscosity ratio
ν	Actual operating viscosity of the oil or the grease base oil [mm2/s]
ν1	Rated viscosity, function of the mean bearing diameter and rotational speed [mm2/s]

The actual operating viscosity, ν, of the lubricant can be determined from the ISO viscosity grade of the oil, or the grease base oil, and the operating temperature of the bearing...[Close Quote]

 

Give that some thought next time you're towing and running 0W20! 

And/Or running 70 in tow mode in other than top gear at Max weight.

 

Hersey is viscosity dependent and viscosity is temperature dependent. 

 

When I first got Pepper it had a 207 F thermostat and the oil heater/cooler in the V-6 models is in the hot tank and is a 5 element stacked plate exchanger that runs counter current. My oil temps ran 220-225 F on normal days of average temperatures and over 235 F at 70 mph on a hot day; 250 F+ ratting her. Something I did  not know until I got my Scan Gauge II. 

 

For most of her life she has run on Red Line HP 5W30 or HP Euro 5W30 whose HTHS viscosity is 3.7 cSt. A hard step up from the DEXOS1Gen2 5W30 call out with a HTHS of 2.9 cSt. And she was fitted with a thermostat of 170 F to lower bulk oil temperatures below what trading that Group III swill for a PAO had already provided. Top line in the graph below the top blue line is the oil temperature vs speed, OEM setup and OEM oil. Green line at the bottom is the current fitment and Red Line Euro 5W30.

 

No one and i mean NO ONE says a word when I drop the oil temperature 25 to 40 degrees but has a cow when I up the viscosity a grade or two. What does that tell you about the understanding of such people? Experts that don't grasp the temperature relationship of the Hersey Equation. No one says a word when I use a 5W30 with a 15W40 HTHS. Again, no understanding. 

 

Or how about the fella's tell me that the saw a huge increase or decrease in hot oil pressure with a grade change. 20 degrees is about one grade and I've added recently another switching to RL HP Euro 5W40 and...nada....a half a needle width on the oil temp. Lack of understanding is killing more equipment that the OEM call outs and these people are the ones I am supposed to take advise from? 

 

 

I don't tell you what I think. I report what I measure. 

Then I do me and let you do you.

 

 

 

Ok here we go. You are trying to describe Hershey-Bulkley for non Newtonian fluid but you are stuck on Newtonian fluids to justify your simplistic understanding of the science. 
Interesting the casual or fawning reader might think you brilliant when really you just like masterdebating in written form. Otherwise known on SOUTHPARK as masterbating. 
Next post we’ll describe how Bulkley plays. 
 

The “Hershey equation” referenced in lubrication is most commonly discussed in terms of the Hersey number, which is a dimensionless parameter used to characterize lubricated contacts. Its classic form is:

where:
    •     = dynamic viscosity of the lubricant,
    •     = sliding velocity,
    •     = normal pressure (or sometimes load per unit length/area).
This equation is foundational in tribology (the study of friction, lubrication, and wear), helping engineers understand how changes in viscosity, speed, or load affect lubrication regimes and friction between surfaces. Modified versions sometimes appear that account for geometry or special operating conditions, such as:

where  is a characteristic length (radius) and  is normal force.
Additionally, for lubricants that are non-Newtonian (e.g., greases), the Herschel–Bulkley equation may be used to describe the flow behavior:

where:
    •     = shear stress,
    •     = yield stress,
    •     = consistency factor,
    •     = shear rate,
    •     = flow index.
This equation generalizes the Bingham plastic and power-law models to better capture the rheological behavior of complex lubricants such as greases and drilling fluids, especially in contexts like bearings and externally pressurized lubrication systems.
In summary:
    •    Hersey number is for evaluating lubrication regimes and predicting friction for Newtonian fluids.
    •    Herschel–Bulkley equation is for modeling non-Newtonian lubricants, relevant when the lubricant shows both yield stress and non-linear viscosity behaviors.

Edited August 16, 2025 by customboss

[customboss]

The Herschel–Bulkley model describes a generalized type of non-Newtonian fluid behavior. Its key feature is that the fluid only starts to flow once a certain yield stress () is exceeded. After that, its viscosity changes nonlinearly with shear rate—meaning that depending on the fluid, it can become either easier (shear-thinning) or harder (shear-thickening) to deform as stress increases. EVERY LUBRICANT YOU USE MUST USE THIS MODEL TO BE DESCRIBED. MAKE SOME NEW GRAPHS PLEASE. 

Mathematical Definition
The relationship is given by:
    •    If the applied shear stress  is below the yield stress :
 (the material behaves as a solid)
    •    If :

Where:
    •    : shear stress (Pa)
    •    : yield stress (Pa)
    •    : consistency index (Pa·s^n)
    •    : shear rate (s^-1)
    •    : flow index (dimensionless)
For shear-thinning fluids:  (e.g., paint)
    •    For shear-thickening fluids:  (e.g., oobleck)
    •    For Newtonian fluids:  and 
Applications & Importance
    •    This model is widely used to describe the flow of muds, slurries, many food products, and drilling fluids.
    •    It provides more accurate rheological descriptions than simpler models, especially when experimental data are available.
    •    By adjusting  and , it can represent various common fluid types: Bingham plastics (linear with yield stress), power-law fluids (shear-thinning/thickening), and more.

In summary, the Herschel–Bulkley model unifies several important fluid behaviors, and is fundamental in characterizing complex materials in engineering and industry. Like lubricants. 

 

Edited August 16, 2025 by customboss

[Grumpy Bear]

https://8020automotive.com/2-4l-ecotec-oil-consumption-causes-solutions/

 

 

 

Brian Sydnes says:

1. April 20, 2023 at 10:32 am

   Agree the engine design can be reliable. When this generation of GDI engines were introduced, there were several things going on that contributed to the oil burning, carbon buildup, timing chain wear. From 2006 to 2010 the use formulation of ethanol based fuel increased from an average of 1-2% to near the full 10% ethanol (E10). This ethanol results in higher carbon, low fuel efficiency and higher fuel dilution rates, especially in GDI engines. The first few years GM was recommending an older Oil Spec, which did not take into account the new problems created by GDI, abrasive soot, fuel dilution, and LSPI. In 2012 they finally came out with Dexos spec oil. Even then a cheap synthetic blend could meet the spec. Under pressure to reduce oil use by regulators and compete with European counterparts, they introduced a new Oil Life Monitor. It took cars to over 10k mile drain intervals. This was disasterous, and finally had to revise the ECM calibration to a max of 7500 miles in 2014 when they were fully aware of excessive wear and carbon build up. Fuel dilution was serious problem and GDI petrol engine created a new form of soot, far more polluting, for more abrasive than often seen in deisel engines. They then came out with Dexos1 oil but still too late and did not fully address the problem. They finally admitted through TSBs that oil consumption was a problem and changed pistons and rings in MY 2013, this was only a head fake. They offered repairs for earlier years but knew it was not a fix.
   They knew GDI was a serious problem, fuel dilution and abrasive soot, intake valve carbon and PCV clogging. Early adopters back in late 1990s and 2000s were aware of these problems. Engines built after that still suffer from carbon clogging rings and timing chain wear. I have 500 oil samples of 2.4l Ecotecs from BlackStone labs. Half are port fuel injected and half GDI. Fuel dilution levels were much higher as well as engine wear with GDI engines. As a result of Low Speed Pre-Ignition in Gen 3 Ecotecs, causing massive engine damage they came out with API SN+, but still didnt address soot or timing chain wear. That did not take place until 2021 with the introduction of API SP, with many new engine tests and specs. Many owners who used premium oil and Top Tier Fuel and ignored the OLM and changed their oil every 3k, have experienced few problems with these engines. Those who used standard oil, cheap fuel and followed the poorly designed OLM suffered from oil consumption, timing chain wear and PCV clogging as early as 80k miles. Just Google GDI soot and GDI fuel dilution, it was and still is a problem. I run Amsoil 0W-40 100% synthetic oil, 2-micron bypass filter, use Top Tier, ethanol fuel, and even with 10k mile drain intervals, the wear levels are 4x less, engine is clean, looks brand new, still factory compression, factory fuel efficiency, and PCV system is completely clear of carbon and intake valves only have minor amounts of carbon build up. I now have 175k miles.

[OnTheReel]

Why would the higher ethanol lead to increased carbon or dilution? 

[Grumpy Bear]

2 hours ago, OnTheReel said:

Why would the higher ethanol lead to increased carbon or dilution? 

 

It doesn't. LOL. I quoted this guy for the bold type portions. He's done allot of testing over a long time with multiple platforms of the motor under consideration. 

[OnTheReel]

I know, rhetorical question.
 

You, (and him to a lesser extent) have that motor figured out top to bottom. Unfortunately since most of the remaining examples are kicking around the backs of “buy here pay here” car lots, it’s pretty much  a lost cause. People will follow the OLM (if that) and these things will continue to fail. 
 

Interestingly the 2.5 LCV that replaced it seems to be fairing a LOT better. Local dealer has a 2017 Acadia 2.5 with 217k on it and it doesn’t appear to be ready for the scrap bin yet.

[KARNUT]

7 hours ago, OnTheReel said:

I know, rhetorical question.
 

You, (and him to a lesser extent) have that motor figured out top to bottom. Unfortunately since most of the remaining examples are kicking around the backs of “buy here pay here” car lots, it’s pretty much  a lost cause. People will follow the OLM (if that) and these things will continue to fail. 
 

Interestingly the 2.5 LCV that replaced it seems to be fairing a LOT better. Local dealer has a 2017 Acadia 2.5 with 217k on it and it doesn’t appear to be ready for the scrap bin yet.

I got a letter a few weeks ago from Honda that the 2016 Odyssey I got from my daughter could use oil. Up until 127K my daughter changed the oil by the minder between 8-10k. I do at 50 percent of the minder around 5K. I told her to do the same with the CRV I gave her in exchange. She follows the minder. The letter also stated that Honda extended the warranty until 160k miles. I’m past that with no oil usage. 

[Atlas]

Are we still talking about the 2.4L in GM's little blobs, and a 10 year old Honda Minivan? Really?

[KARNUT]

28 minutes ago, Atlas said:

Are we still talking about the 2.4L in GM's little blobs, and a 10 year old Honda Minivan? Really?

You’re missing the point as usual. You’re locked in a mindset that inhibits growth. The point of threads like these are reliability and longevity. Of course I’m talking to a rock and wasting my time I’m afraid, but I tried. What time is your shift at McDonald’s? 

[Atlas]

23 minutes ago, KARNUT said:

You’re missing the point as usual. You’re locked in a mindset that inhibits growth. The point of threads like these are reliability and longevity. Of course I’m talking to a rock and wasting my time I’m afraid, but I tried. What time is your shift at McDonald’s? 

 

I'd rather work than be on welfare. Inhibited growth is driving an old minivan and thinking anyone cares that it has high mileage. Guess what? Nobody cares.