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

[viven44]

Smart man!

I got roasted when I asked the question about 8 qts not being enough. Granted things may have changed with the oil pan size, but a number of years ago, I think up to about 2015, all the V8 trucks indicated 8.5 qts with filter. Then with a single piece of paper, GM updated the oil fill with filter from 8.0 to 8.5 qts, nothing changed with the motors that had already been been built.

I checked my oil level when I purchased the truck and before the first oil change at 500 miles and matched the level on the dipstick. 8.0 qts did not even touch the stick when I initially poured the oil in. Sure I could have waited until overnight, but this was not my plan.

I run 9 qts and have ZERO issues. More oil to be diluted by fuel, more oil to get dirty, more oil to lubricate the engine. Given all the 6.2l problems are OIL related, this is not going to hurt anything. I also WILL NOT run 0W20 oil in the engine. Either 5W30 or 0W40. After tracking the oil temps on longer highway cruises, I am going to switch to 0W40 and see what happens with oil temps and the oil analysis.

The 6.2l in the Camero's spec 0W40 and the DI 5.3l and 6.2l in boats (doubt they have DFM in these) spec 5W30. 0W20 was speced because GM sold too many 6000 lb trucks and they were worried about the CAFE numbers.

If using 9qts puts you at or below the max level on the dipstick (of course when checking on level ground), I'd say you are good. If you are a lot higher than the dipstick max by using 9qts that would be concerning. We don't want the crank aerating the oil.

 

[jfoj]

Fine line between "lugging" or Low RPM/High Loading and High RPM/High Loading. High RPM full throttle runs just "wears" things out due to the sheer number of revoltions the engines makes as long as you do not stress things to the breaking point. Low RPM "lugging" just beats the engine down in a much shorter period of time and loads things like bearings probably beyond their limits.

The issue to get these 6000 bricks to obtain 18 MPG or more on the highway, the large engine cannot be spinning too many RPM. So the TCU (Transmission Control Unit) really manages Torque. The 6.2l puts out a lot of Torque at lower RPM so the transmission is programmed to use the Torque to keep the RPM's low. Behavior is different on the 5.3l as it does not have the raw Torque the 6.2l has, so it runs at higher RPM's to pull grades, downshifts a lot more. It may run at similar RPM on flat surfaces as the 6.2l, but find a small inclince and the 5.3l is spinning more RPM to keep up speed.

This lower RPM operation puts a lot of load on the engine, specificaly the rod bearings. With the oil temp these engines run on the highway at 225F+, and I only have a good 1st set of data for like 64F ambient temps, not the crazy Summer temps of the high 90's-100's and the pavement being like 130F from cooking in the sun all day, 0w20 starts to look and operate more like 0W10 and under extreme conditions the oil is more like 0 weight overall. Not ideal.

It is not the engines are not getting enough oil, it could be, but what oil the bearings are getting is just too thin to hold up under the extreme loading and keep the engine bearings properly lubricated and componets cool enough. Oil also has a job at cooling the engine, once the oil gets too hot, it cannot perform its intended lubrication purpose and the oil viscosity will need to be adjusted for the operation requirements of the engine at higher oil temps.

While thinner oil has lower pump loss and lower "frictional loss" or drag on moving parts rotating on the bearing surfaces, you can gain Horsepower using a lower viscosity oil. There is balancing point to keep the oil cool enough so it does not thin out more than expected and under severe duty thinner oil may not provide enough engine protection with a sufficient oil wedge in the bearing area once the oil temp increases and the oil thins out. UNFORTUATELY GM recommends 0W20 for towing as well! No way in hell I would run 0W20 with the oil temps I see when the truck is loaded with nothing but a full tank of fuel and my smiling face.

Pretty much all of these 6.2l failures lately are bearing problems, and usually bearing problems are due to lubrication problems and overheating due to insuficient cooling. And for all the 20,000+ 6.2l failures, these are highly unlikely any sort of manufacturig problem or defective part at this point in their lifespan. Many environmental factors, useage factors, maintenance factors and the common element to almost all the engine failures is 0W20 oil.

 

[jfoj]

If using 9qts puts you at or below the max level on the dipstick (of course when checking on level ground), I'd say you are good. If you are a lot higher than the dipstick max by using 9qts that would be concerning. We don't want the crank aerating the oil.

9 qts may be slightly above the full hash mark, but there is plenty of room below the windage tray and I have checked for foaming or aeration and seen nothing. Keep in mind, just check the engine oil immediately after shutting down the engine and see where the oil is shown on the dipstick, oil not fully drained back from the top end of the engine block.

Based on a number of folks indicating the full measure is around 8.7 quarts, we are talking about less than 10 oz extra oil in an area the footprint of the oil pan. You are looking at probalbly less than 1/4" overall.

 

[Vladimir2306]

Dump the 0W20 and move up to 5W30 or 0W40. The same 6.2 in the Camero is spec'ed for 0W40. And trust me the Camero does not weight 6000 lbs and run below 1700 RPM on the highway!

This is not the first time I write here. Our engines cannot have 5-30 and 0-40. The engine is designed for 0-20 for the entire service life of the car. The oil pump is designed for this oil, giving it a thicker one, and the pump gives pressure designed for 0-20, you violate the lubrication regulations of the parts laid down by the manufacturer.

 

[Vladimir2306]

Smart man!

I got roasted when I asked the question about 8 qts not being enough. Granted things may have changed with the oil pan size, but a number of years ago, I think up to about 2015, all the V8 trucks indicated 8.5 qts with filter. Then with a single piece of paper, GM updated the oil fill with filter from 8.0 to 8.5 qts, nothing changed with the motors that had already been been built.

I checked my oil level when I purchased the truck and before the first oil change at 500 miles and matched the level on the dipstick. 8.0 qts did not even touch the stick when I initially poured the oil in. Sure I could have waited until overnight, but this was not my plan.

I run 9 qts and have ZERO issues. More oil to be diluted by fuel, more oil to get dirty, more oil to lubricate the engine. Given all the 6.2l problems are OIL related, this is not going to hurt anything. I also WILL NOT run 0W20 oil in the engine. Either 5W30 or 0W40. After tracking the oil temps on longer highway cruises, I am going to switch to 0W40 and see what happens with oil temps and the oil analysis.

The 6.2l in the Camero's spec 0W40 and the DI 5.3l and 6.2l in boats (doubt they have DFM in these) spec 5W30. 0W20 was speced because GM sold too many 6000 lb trucks and they were worried about the CAFE numbers.

How did you conclude that all the problems of the 6.2 are related to the oil? There are no investigation results yet. At the same time, the 0-20 oil was also on the K2 generation, on which people drove hundreds of thousands of miles around the world.

 

[jfoj]

This is not the first time I write here. Our engines cannot have 5-30 and 0-40. The engine is designed for 0-20 for the entire service life of the car. The oil pump is designed for this oil, giving it a thicker one, and the pump gives pressure designed for 0-20, you violate the lubrication regulations of the parts laid down by the manufacturer.

Just do your research, the same oil pump is used on the 6.2l in the Camero and depending on what documentation you find and read for the Camero the recommened engine oil is either 5W30 or 0w40.

The Camero LT1 engine is pretty much the same as the L87 with the exception of a few different parts and tuning for higher output.

 

[Vladimir2306]

Just do your research, the same oil pump is used on the 6.2l in the Camero and depending on what documentation you find and read for the Camero the recommened engine oil is either 5W30 or 0w40.

The Camero LT1 engine is pretty much the same as the L87 with the exception of a few different parts and tuning for higher output.

We've already discussed it, Camaro is a sports car. It drives at high revs, its job is to accelerate quickly. Tahoe/Yukon drives slowly, it drives mostly at low revs. The oil pump, even if it is the same, has different programming of the pressure it creates. At high revs, you need thicker oil, the lower the operating revs, the thinner the oil needs to be. That's why we have 0-20, and on Camaro it's 0-40.

 

[jfoj]

How did you conclude that all the problems of the 6.2 are related to the oil? There are no investigation results yet. At the same time, the 0-20 oil was also on the K2 generation, on which people drove hundreds of thousands of miles around the world.

The majority of bearing falures almost always end up being oil related. Dirt in the oil usually made up of soot and/or sludge and hard carbon or contaminated oil that is broken down and has a loss of viscosity, most commonly fuel in these DI engines. Oil starvation is also a possibility, but this is not a common denominator I am seeing with the current 6.2l engine failures.
The K2 generation was not without its problems, but it was also a slightly different beast when it comes to both the engine and the platform. I big difference is the radiator shutters in the newer generation of these trucks for again MPG on the highway, to make a brick more areodynamic. Not entirely sure how much closing the shutters elevates the engine oil temperature, but it cannot help it.

I have not really put this out here yet, but I am really starting to think the DFM system is also another major contributing factor to the current generation of L87 failures.

With the AFM system you pretty much drop either 2 or 4 cylinders at a time. Pretty much a "symetrical" situation where you would never have fewer than 4 cylinders rotating the engine mass and propelling the vehicle. So the entire engine load is spread across no fewer than 4 rod bearings.

With the DFM system you can end up with an asymetrical operation of a single cylinder rotating the engine mass and propelling the vehicle. Then add to this the fact that the cylinder deactivation is constantly jumping around in different sequences. It is not likely the same 1 cylinder is always being called upon.

With the DFM system you have a crazy hodge podge of possibly 0 to 8 cylinders driving/rotating the engine. Assume, but have not confirmed that possibly during Decel With Fuel Cutoff (DFCO) the DFM engine may possibly deactivate all 8 cylinders for a period of time. But any other time, the system is jumping around and possible rotating the engine mass with as few as 1 cylinder. Think about the rod bearing loading when a single cylinder is trying to turn the engine rotating mass, compressing air in the deactivated cylinders, turning the torque converter and transmission and trying to somewhat propel the vehicle. Think about the forward and backward loading on the crank thrust bearing when all the crazy cylinder deactivation is going on. I beleive there are like 27 different cylinder deactivation combinations/routines for the DFM system vs probably 2 general combinations for the AFM system, might be more when you factor load into the equation, but in general is it pretty much a 4-6-8 cyliinder configuration not far from the early Cadillac V8 from the early 1980's.

While operating on as few as 1 cylinder may be great in philosophy, not sure it is wise in practice. I think we are all seeing down side of all the effort to squeeze a few more MPG out of a 6000 brick.

Too many parts, too many instructions, too many variables that cannot be controlled outside of the lab/developement area, too many things to go wrong.

 

[jfoj]

We've already discussed it, Camaro is a sports car. It drives at high revs, its job is to accelerate quickly. Tahoe/Yukon drives slowly, it drives mostly at low revs. The oil pump, even if it is the same, has different programming of the pressure it creates. At high revs, you need thicker oil, the lower the operating revs, the thinner the oil needs to be. That's why we have 0-20, and on Camaro it's 0-40.

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. Also 0W20 is not 0W20 once you add gasoline to it and warm it above 212F/100C. It quickly becomes 0 weight oil or less! The only reason the trucks and many of the other models are running 0W20 oil is for the CAFE fuel economy ratings. Point of reference, in 2022 GM sold about 25,000 Cameros and almost 900,000 light trucks! The 6000 bricks are killing the CAFE numbers, so they need to focus on how to squeeze very 1/10 of a MPG of fuel economy out of the high volume sellers to help balance the CAFE average.

The oil pump for the LT1 and L87 use the same spring in it for the variable displacement function. As for the 2nd stage ECM controlled oil pressure "boost", I would bet the LT1 and the L87 are pretty much programmed very similiar, which is actually unfortunate for the L87 as the 2nd stage oil pressure "boost" should be programmed for engine LOAD and RPM, not just RPM.

Add the EXTREME rod beariing loading with a light weight compromised oil with constand engine loading near 100% at RPMs typically below 2000 RPM when encountering even the slightest grade, nothing good will come from all of this.

Look NASCAR engines typically run very thin oils, probably 0W20 or possibly a non multiweight oil of around 20 weight. They run are built for high Revs and to accelerate quickly. But NASCAR and other racing engines often run lower viscosity oil for a few reasons, mainly due to reduced oil drag in the bearing journals which equates to more net power or less parasitic load and loss of engine power.

BUT, understand a few things, race cars operate in a very controlled enviroment and the engines are purpose built and do not need to last more than 500 miles. They have larger dry sump oiling systems and very good oil cooling. They also sometimes pre-heat the oil before hitting the track and the warm up laps are both to warm up the tires and the engine oil before starting to race at 8000+ RPM.

Look at the track suggested oil GM recommends, they recommend things like 15W50 or even seem to feel the 0W40 is also adequate on some platforms. The higher viscosity oil that is recommended for track purposes is because the oil cooling is not adequate, there is a balance between daily driving and racing, and if the vehicles were build with large enough oil capacity and cooling for racing this would be a problem for daily driving.

I will have more data in the next few months at the Summer temps hit close to 100F and the road surface temps are 130F+ and while driving for 2-6 hours and I am guessing the oil temps are not going to be ideal for 0W20 engine oil to protect the High Torque/Low RPM operation of the 6.2l is these trucks. I will not have data for towing as I have no plans for towing at this point.

 

[Vladimir2306]

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. Also 0W20 is not 0W20 once you add gasoline to it and warm it above 212F/100C. It quickly becomes 0 weight oil or less! The only reason the trucks and many of the other models are running 0W20 oil is for the CAFE fuel economy ratings. Point of reference, in 2022 GM sold about 25,000 Cameros and almost 900,000 light trucks! The 6000 bricks are killing the CAFE numbers, so they need to focus on how to squeeze very 1/10 of a MPG of fuel economy out of the high volume sellers to help balance the CAFE average.

The oil pump for the LT1 and L87 use the same spring in it for the variable displacement function. As for the 2nd stage ECM controlled oil pressure "boost", I would bet the LT1 and the L87 are pretty much programmed very similiar, which is actually unfortunate for the L87 as the 2nd stage oil pressure "boost" should be programmed for engine LOAD and RPM, not just RPM.

Add the EXTREME rod beariing loading with a light weight compromised oil with constand engine loading near 100% at RPMs typically below 2000 RPM when encountering even the slightest grade, nothing good will come from all of this.

Look NASCAR engines typically run very thin oils, probably 0W20 or possibly a non multiweight oil of around 20 weight. They run are built for high Revs and to accelerate quickly. But NASCAR and other racing engines often run lower viscosity oil for a few reasons, mainly due to reduced oil drag in the bearing journals which equates to more net power or less parasitic load and loss of engine power.

BUT, understand a few things, race cars operate in a very controlled enviroment and the engines are purpose built and do not need to last more than 500 miles. They have larger dry sump oiling systems and very good oil cooling. They also sometimes pre-heat the oil before hitting the track and the warm up laps are both to warm up the tires and the engine oil before starting to race at 8000+ RPM.

Look at the track suggested oil GM recommends, they recommend things like 15W50 or even seem to feel the 0W40 is also adequate on some platforms. The higher viscosity oil that is recommended for track purposes is because the oil cooling is not adequate, there is a balance between daily driving and racing, and if the vehicles were build with large enough oil capacity and cooling for racing this would be a problem for daily driving.

I will have more data in the next few months at the Summer temps hit close to 100F and the road surface temps are 130F+ and while driving for 2-6 hours and I am guessing the oil temps are not going to be ideal for 0W20 engine oil to protect the High Torque/Low RPM operation of the 6.2l is these trucks. I will not have data for towing as I have no plans for towing at this point.

You use a lot of phrases like "Probably", "Possibly". You build hypotheses based on the wrong facts. Yes, the oil is getting thinner, well, the Manufacturer knows this and took it into account.
I'll tell you about summer and heat, the oil temperature in summer is about 120-130C, or 250-260F, so what? All oils work that way, the 0-20 oil that I pour in has a flash point of 220C. For it, working in the 6.2 range is normal.
Look, the 2025 models have been running for about 5-6 months. They have already driven more than 100-1000 miles, at which the 21-24 models broke down. There is no wave of failures on them. The oil is the same 0-20. DFM also works. AFM/DFM works for everyone on 900, K2 and T1 without problems.
It is very strange for me how one can take responsibility, advising oil different from the manual. We also have advisers in our Forums who advise pouring thicker, without having any engine calculation parameters. And who will answer then? You? Hardly.
I am sure that the result of the investigation will be just some nonsense, so as not to get into huge lawsuits, but in fact, GM has already fixed everything in the 2025 models. They just don’t advertise it. Like, for example, with the valve covers, where on models up to 2023 there was a 1 cm sealant leak, which resulted in increased oil consumption, and since 2023 the valve covers have become without this leak.

 

[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 Sommerfeld numerator that increases will reduce eccentricity.
Any term in Sommerfeld 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