What is the quarts "range" on the dipstick on these trucks?

[jfoj]

@Vladimir2306

I guess you have this all figured out.

I think you were also the one that told me the engine oil heats up quicker than the coolant temperature as well.

I do the best to clearly articulate what I firmly understand and know for fact, but I have found over the years, often you need to be careful about stating fact on some items that have running changes or have slightly different build configuration.

If you have evidence that the oil temps are running 120-130C, or 250-260F in the Summer, please provide the data, I would like to see it. I will find out here in the next 4 months first hand if this is the case. You should see what happens to oil viscosity 100C/212F, it is not going to help these engines.

Anyway, you do you.

Unfortantely todays vehicles are not necessarily designed for durability and reliability. There are too many conflicting requirement put on not only the automotive industry but almost anything that used energy these days. These products have become over priced, over complicated and are very tempermental to how they are used and need to be maintained. We can all thank the government officials with limited or no technical background for doing this to all the consumers.

 

[Vladimir2306]

@Vladimir2306

I guess you have this all figured out.

I think you were also the one that told me the engine oil heats up quicker than the coolant temperature as well.

I do the best to clearly articulate what I firmly understand and know for fact, but I have found over the years, often you need to be careful about stating fact on some items that have running changes or have slightly different build configuration.

If you have evidence that the oil temps are running 120-130C, or 250-260F in the Summer, please provide the data, I would like to see it. I will find out here in the next 4 months first hand if this is the case. You should see what happens to oil viscosity 100C/212F, it is not going to help these engines.

Anyway, you do you.

Unfortantely todays vehicles are not necessarily designed for durability and reliability. There are too many conflicting requirement put on not only the automotive industry but almost anything that used energy these days. These products have become over priced, over complicated and are very tempermental to how they are used and need to be maintained. We can all thank the government officials with limited or no technical background for doing this to all the consumers.

Yes, I know what viscosity oils have at 100C. Oil 0-20 has 8.52 mm²/s, oil 0-40 has 13.4 mm²/s, which is logical, oil with index 40 is almost twice as thick as oil 20. Let me give you an example. You are not a young man anymore, are you? You probably have problems with thick blood. And when a person's blood is thicker than normal, it is bad. And when blood is thinner than normal, it is also bad. Normal is good, 0-20 is good for our engines, any deviation from it is bad.
As for the fact that engines were reliable before, this is also a mistake. Engines also broke down, and a rare 900 reached 200 thousand miles without major repairs. And when several examples that drove without problems up to 300 thousand miles are used to draw a conclusion about the entire generation, this is not true. In Russia, in Statistics, this is called "Survivorship Bias." This is a very interesting phenomenon.

 

[viven44]

We would be far better off with higher Revs on this plaform, the 5.3l does seem to have higher Revs overall because it lacks the Torque of the 6.2l and needs to keep up speed by the TCM downshifting more gears.

@jfoj I am starting to believe in the past discussion that the aggressive gear shifting that sets up the engine to lug most of the time, combined with people not using premium fuel might really be hurting a good percentage of these engines. Many of the failures do seem to be happening at highway speeds if I am not mistaken so thats good evidence.

GM should (I believe) reprogram the TCM to make the 6.2L shift more like the 5.3L. Honestly there is extra torque, but clearly this "small block" engine is not able to take the beating like a traditional big block that ran on all cylinders, so GM needs to revise the operation where the engine revs more, just like the 5.3L..... I know its nice to see that both 5.3L and 6.2L get the same highway fuel mileage, but its no fun if the 6.2L's rod bearings have to take a beating to get the fuel economy. I know consumers are primarily looking at fuel economy and when you see all the 3 row lifted-cars get close to 30mpg, GM must at least offer 20mpg on these body on frame vehicles to sell them understandably. Reliability first though.

 

[jfoj]

Yes, I know what viscosity oils have at 100C. Oil 0-20 has 8.52 mm²/s, oil 0-40 has 13.4 mm²/s, which is logical, oil with index 40 is almost twice as thick as oil 20. Let me give you an example. You are not a young man anymore, are you? You probably have problems with thick blood. And when a person's blood is thicker than normal, it is bad. And when blood is thinner than normal, it is also bad. Normal is good, 0-20 is good for our engines, any deviation from it is bad.
As for the fact that engines were reliable before, this is also a mistake. Engines also broke down, and a rare 900 reached 200 thousand miles without major repairs. And when several examples that drove without problems up to 300 thousand miles are used to draw a conclusion about the entire generation, this is not true. In Russia, in Statistics, this is called "Survivorship Bias." This is a very interesting phenomenon.

I do not think the blood really gets thicker as you age, the pipes have sludge buildup and they become smaller!!!! This in terms raised the blood/oil pressure, but for the human body the higher blood/oil pressure is not a good thing, higher oil pressure on the 6.2l might be a benefit!

 

[jfoj]

@jfoj I am starting to believe in the past discussion that the aggressive gear shifting that sets up the engine to lug most of the time, combined with people not using premium fuel might really be hurting a good percentage of these engines. Many of the failures do seem to be happening at highway speeds if I am not mistaken so thats good evidence.

GM should (I believe) reprogram the TCM to make the 6.2L shift more like the 5.3L. Honestly there is extra torque, but clearly this "small block" engine is not able to take the beating like a traditional big block (just compare the size of the main and rod bearings on this engine vs a 454 big block...!!!) and definitely not on 2 cylinders out of the 8 allegedly at times so GM needs to revise the operation where the engine revs more, just like the 5.3L..... I know its nice to see that both 5.3L and 6.2L get the same highway fuel mileage, but its no fun if the 6.2L's rod bearings have to take a beating to get the fuel economy. I know consumers are primarily looking at fuel economy and when you see all the 3 row lifted-cars get close to 30mpg, GM must at least offer 20mpg on these body on frame vehicles to sell them understandably. Reliability first though.

Initially I did not think the transmisson was even downshifting, it just seemed the engine was loading up on slight grade increases and these are not steep or very long on the specific route I take often.

Still feel the DFM with a single cylinder trying to spin the rotating mass and propel the vehicle is not ideal as well, lots of load on a single rod bearing. Funny how the AFM had 4 cylinders doing the same job and for the most part the only failures were lifters/camshafts probably a lot to do with OCI, rather than "defects".

Then once I was able to track in real time and log the transmission behavior, I would see the transmission was downshifting from 10th to 9th gear, but it was really hard to tell/feel in the seat of the pants or see on the tachometer. Turns out the RPM would only increase about 100 RPM.

The poor/rich mans way of dealing with the Torque loading on the 6.2 is to just drive with the transmission in 8th gear on the highway. While I have not logged this behavior, you remove 2 Over Drive gears from the equation. You will CLEARLY take a hit on fuel economy, but at what cost? $10-$20 a trip? You could take a lot of trips to cover the inconvienance and/or cost of an engine replacement. I do not think anyone buys these 6000 lb bricks for fuel economy. While I think we all appreciate the fuel ecomony that these trucks get, at what cost in the long run???

I have no idea what fuel economy my truck would get if I had not disabled the Auto Stop/Start and DFM system, but for the almost 6000 miles I have on the truck the running Fuel Economy average is 17.5 MPG for the life of the vehicle at this point.

 

[Vladimir2306]

I do not think the blood really gets thicker as you age, the pipes have sludge buildup and they become smaller!!!! This in terms raised the blood/oil pressure, but for the human body the higher blood/oil pressure is not a good thing, higher oil pressure on the 6.2l might be a benefit!

Bingo, that's exactly what I'm getting at. The pump doesn't make the pressure higher, it creates the pressure that it's set to, under the oil 0-20. But what happens if the pressure under the oil is 0-20, and you fill it with 0-40. What happens then?

 

[jfoj]

Bingo, that's exactly what I'm getting at. The pump doesn't make the pressure higher, it creates the pressure that it's set to, under the oil 0-20. But what happens if the pressure under the oil is 0-20, and you fill it with 0-40. What happens then?

The engine lasts longer! Because of 0W40 or 5W30 has a safety margin because it probably ends up more like 0W20 once the oil is contaminated with fuel and/or the temperature is above 100C/212F. 5W30 or 0W40 has absolutely no negative effect on the oil pump. If you do your research you will see in many other applications these exact same engines and same engines without DFM all are speced for either 5W30 or 0W40, some are speced for higher viscosity oil for track use.

The variable displacement pump is designed to self regulate, unlike the gerotor pump. But even the gerotor oil pumps have pressure relief valves typically built in, that will release oil pressure if is higher than the set point. The variable displacement pump functions almost exactly like an automatic transmission fluid pump. A rather interesting and clever design.

 

[Vladimir2306]

The engine lasts longer! Because of 0W40 or 5W30 has a safety margin because it probably ends up more like 0W20 once the oil is contaminated with fuel and/or the temperature is above 100C/212F. 5W30 or 0W40 has absolutely no negative effect on the oil pump. If you do your research you will see in many other applications these exact same engines and same engines without DFM all are speced for either 5W30 or 0W40, some are speced for higher viscosity oil for track use.

The variable displacement pump is designed to self regulate, unlike the gerotor pump. But even the gerotor oil pumps have pressure relief valves typically built in, that will release oil pressure if is higher than the set point. The variable displacement pump functions almost exactly like an automatic transmission fluid pump. A rather interesting and clever design.

Why do you keep repeating the same thing? There is no greater safety margin for 0-40 or 5-30 oil. After all, these oils were changed in the same way as now. The replacement schedule has not been shortened. These oils, just like 0-20, are contaminated with fuel, everything is the same there. And if dilution with fuel is taken into account in an engine with 5-30 or 0-40 oil, then dilution with fuel of 0-20 oil is taken into account in absolutely the same way. Or do you really think that this is a surprise for engine developers? In the same way, fuel dilution is taken into account in the new Toyota Land Cruiser, where 0-16 oil is poured.
I know perfectly well that there is protection against high oil pressure, I am telling you about something else. Your pressure will not be high, it will be as it was set for 0-20 oil. And when you try to push oil through this pressure that is twice as thick, it means that most likely half as much oil gets to the friction point.
And if half as much oil gets there, it causes increased wear of parts. Is this simple truth not getting through?
Now...the most harmful mode for the engine is the moment of starting after a long period of inactivity, when the oil has already flowed into the crankcase. And the task of the oil pump is to pump oil into the engine before the engine starts.
But the pump pumps creating pressure under the oil 0-20. Even if it is diluted with fuel, which, I repeat, is calculated in advance by the manufacturer. And by pouring in oil 5-30 you yourself, with your own hands, reduce the amount of oil to the point of cold start.

 

[blanchard7684]

I'd like to chime in and also state that I put the dipstick up to max range and that is typically at least 8.5 quarts with a full filter.

Oil viscosity is related to rotor eccentricity. Too much eccentricity and you have metal to metal contact. Too little eccentricity and you get high bearing temps and vibration problems (the kind you don't feel in your seat but will wreck a crank and bearings nonetheless).

This is all connected via the Sommerfeld relation:



Eccentricity term is on right hand side. Sommerfeld number is on left hand side.

u is viscosity, omega is rpm, W is load, L is bearing width, R is bearing radius, C is bearing clearance.

You can see there is an L^3/C^2 term here where eccentricity is suuuper sensitive to clearance and width. This isn't an issue in this discussion about viscosity.

What is left is viscosity, Load W, and RPM.

Through iterative approaches the following can be said.

Any term in numerator that increases will reduce eccentricity.
Any term in denominator that increases will increase eccentricity.

So...by only increasing rpm, the eccentricity is reduced. Therefore reducing viscosity will counteract this and induce eccentricity. So if your application is constant high rpm it would actually favor lower viscosity. Oil cooling will need to be tightly controlled to keep this situation under control.

Increasing load will increase eccentricity. Therefore increasing viscosity will counteract this and reduce the eccentricity. So if your application is for towing or accelerating uphill or a super heavy SUV, the load is high at every RPM. Therefore, this would favor higher viscosity to reduce eccentricity.

Worst case is obviously high loads and low rpms. This would give maximum eccentricity. The oil wedge reaction force against this is dependent on the viscosity.





This is a "use case" that is very typical of SUVs and trucks but also drag racing. So with high loads and low rpm the viscosity must be higher to keep eccentricity managed.

Downside to running viscosity too high (SAE 50+) in these situations is cold oil...therefore the mutli viscosity grades are helpful in giving a range of viscosities keep eccentricity from getting too low and causing vibration if there is extended low load, high rpm situations while oil is cold.

 

[viven44]

Thanks for sharing these equations. Very educational.

I was just about to say the bearing clearance is a big component in all this and I like the way they used to do back in the day where oil viscosity was recommended in the manuals based on ambient temp and use conditions. Constant high temp and loaded applications called for higher viscosity for sure. Here, running on 2 cylinders may be construed as a high load scenario perhaps??

Anyone here have access to factory service manuals? That ought to clarify things a bit more

Examples from old GM manuals