My first post on here, I've read a lot of threads on this site. Never thought I'd post a thread myself, but here I am!
Hello everyone, going to proceed to beat a dead horse, as it’s been done time and time again. I’m confused, and don’t want to be misled, nor provide information that may mislead others. After looking at specs sheets and attempting to understand these engines I’ve gone down several rabbit holes leading me to believe in the end that the 5w30 suffices. I’m curious on why folks recommend 5w40, and even 5w50 over 5w30? What’s the evidence behind this recommendation, and is there information that can be provided as to why? I can’t just accept “so and so engine builder uses this weight all the time”. I get emissions plays a part in oils, but even then, oils are much more advanced than they were even 10 years ago. I’m currently running Liqui Moly 5w30, and will testing this oil every 4500-5000 miles. I will provide updates to this thread as time goes on to see wear in the engine, including: TBN, TAN, detergents, and materials found. I don’t baby the car, so you should see pretty clear information for engines that get put through their paces. Now onto my comparison.
These are the two oils I'm comparing, not neccesarily to choose one or the other. Just to try and better understand the difference between these oils, and whether going with a 40 weight is truly going to benefit this engine.
Added is a photo of a table comparing Liqui Moly Special Tech 5w30 vs Amsoil European Formulate 5w40.
When thinking just on the name and labeled oil ie: 5w30, 5w40, 5w50, two things come to mind.
One: The Amsoil will be thicker
Two: It should have better viscosity under high-heat and pressure.
With these two things in mind see the table I’ve attached. When looking at the table, it becomes clear that thought 1 was correct. Amsoil is indeed a thicker oil. Now in terms of actual performance under load, the HSHT viscosity numbers tell another story. Where the oils now are very close in likeness. The Liqui Moly provides just as a good of a viscosity as the Amsoil under high heat and shear where it counts. During normal operations the LM @ 100C it is indeed a lower viscosity, but within the range of typical 5w40 oils… You want the oil to flow to the places it needs to be, and create that hydrodynamic film layer to protect surfaces such as bearings. You also want the oil to be resistant to being pushed out and away from those surfaces. Looking at the VI (Viscosity index) you can see these two oils are only 3 points away, meaning they are both very stable oils throughout the temperature range.
If we’re talking about oil burning off, there are a few factors. A couple being, flash point, and how much of that oil is getting past the rings under boost. The thing is, these engines have highly developed PCV systems to prevent oils from making their way past the rings by alleviating pressures in the crankcase that is caused by increased pressures in the combustion chamber. With that being said when looking at viscosity you can see the 5w30 is about 1.6 points away from the 5w40, very close and still technically a 5w40 consistent viscosity. With the VI being just about the same, the stability factor and the idea of the 5w30 thinning out quicker is relatively minor and I don’t believe a make or break. When talking flashpoint, you can see that the Liqui Moly actually has a higher flash point, meaning the oil will hold up to higher temperatures better when exposed to flame. Now the difference in temperature is minor at about 18 degrees Fahrenheit. When looking at the NOACK values, which indicated %weight loss of oil through evaporation. the amsoil loses .8% less oil. Is this even something to worry about? When doing such short oil change intervals, less than a percent loss of oil? That's negligible at best in my opinion when these engines hold a ton of oil to begin with.
Again I’m asking “Why the 5w40 or the 5w50?” What is the actual reasoning behind this? If you’ve had a failure of an engine, was it due to the oil? There are several factors that go into why an engine could fail. Typically, I’ve seen on S65 and S62 engines that going with a lower viscosity meant potentially not having that hydrodynamic layer under higher pressures leading to bearing failure. Now those engines have really tight tolerances. Does the S63T4 suffer from this same issue? I know they have changed materials used within, not knowing exactly if the bearings are the same? if the clearances change? not too sure...I’ve not read at all about bearings being an issue, or cylinders walls being eaten away due to lack of that lubrication…Keep in mind the S63T4 has one oil pump, a suction pump, and 16 oil spray nozzles. I highly doubt lubrication is an issue, and when keeping in mind viscosity, a lower viscosity means a better flowing oil. If the engines were indeed designed for 5w30, then going with a higher viscosity means the oil pumps work harder by nature. I need more confirmation on this, as I’m getting contradicting information. Euro vs US, etc ,etc. I know Euro emission regulations are much more stringent, then here in the US. With things like OPF making there way even into M cars now. So not sure why a 40 weight would be recommended there vs. a 30 weight here? I’ve only really seen higher weights used if per-say you add more power than the engine was initially designed for as now you’re putting more pressure on the bearings than intended, or your engines tolerances are worn to the point where a thicker oil is now needed. When talking about a stock engine, why deter from the recommended? Is the recommended a lie? And who could answer this?
In the end I’m just trying to understand these engines better, if by going 5w30 I made a mistake, then so be it. It’s a learning process and I’m all for that, but I highly doubt this would lead to any sort of engine failure due to that. The oils in a 3-5K mile change interval aren’t even in the engine long enough to degrade to a point of damage. Especially since I don’t track the car. What’re your thoughts? Anyone have insider information on this? Engine builders, why do you use what you use? What have you seen? And can you provide some evidence to further clarify your reasoning for the weight you choose. Testing, failure diagnosis, etc., are all welcome!
Thanks everyone. I know it’s a long post, but there is a lot to talk about and I'm looking forward to having a solid, and informative conversation.
Hello everyone, going to proceed to beat a dead horse, as it’s been done time and time again. I’m confused, and don’t want to be misled, nor provide information that may mislead others. After looking at specs sheets and attempting to understand these engines I’ve gone down several rabbit holes leading me to believe in the end that the 5w30 suffices. I’m curious on why folks recommend 5w40, and even 5w50 over 5w30? What’s the evidence behind this recommendation, and is there information that can be provided as to why? I can’t just accept “so and so engine builder uses this weight all the time”. I get emissions plays a part in oils, but even then, oils are much more advanced than they were even 10 years ago. I’m currently running Liqui Moly 5w30, and will testing this oil every 4500-5000 miles. I will provide updates to this thread as time goes on to see wear in the engine, including: TBN, TAN, detergents, and materials found. I don’t baby the car, so you should see pretty clear information for engines that get put through their paces. Now onto my comparison.
These are the two oils I'm comparing, not neccesarily to choose one or the other. Just to try and better understand the difference between these oils, and whether going with a 40 weight is truly going to benefit this engine.
Added is a photo of a table comparing Liqui Moly Special Tech 5w30 vs Amsoil European Formulate 5w40.
When thinking just on the name and labeled oil ie: 5w30, 5w40, 5w50, two things come to mind.
One: The Amsoil will be thicker
Two: It should have better viscosity under high-heat and pressure.
With these two things in mind see the table I’ve attached. When looking at the table, it becomes clear that thought 1 was correct. Amsoil is indeed a thicker oil. Now in terms of actual performance under load, the HSHT viscosity numbers tell another story. Where the oils now are very close in likeness. The Liqui Moly provides just as a good of a viscosity as the Amsoil under high heat and shear where it counts. During normal operations the LM @ 100C it is indeed a lower viscosity, but within the range of typical 5w40 oils… You want the oil to flow to the places it needs to be, and create that hydrodynamic film layer to protect surfaces such as bearings. You also want the oil to be resistant to being pushed out and away from those surfaces. Looking at the VI (Viscosity index) you can see these two oils are only 3 points away, meaning they are both very stable oils throughout the temperature range.
If we’re talking about oil burning off, there are a few factors. A couple being, flash point, and how much of that oil is getting past the rings under boost. The thing is, these engines have highly developed PCV systems to prevent oils from making their way past the rings by alleviating pressures in the crankcase that is caused by increased pressures in the combustion chamber. With that being said when looking at viscosity you can see the 5w30 is about 1.6 points away from the 5w40, very close and still technically a 5w40 consistent viscosity. With the VI being just about the same, the stability factor and the idea of the 5w30 thinning out quicker is relatively minor and I don’t believe a make or break. When talking flashpoint, you can see that the Liqui Moly actually has a higher flash point, meaning the oil will hold up to higher temperatures better when exposed to flame. Now the difference in temperature is minor at about 18 degrees Fahrenheit. When looking at the NOACK values, which indicated %weight loss of oil through evaporation. the amsoil loses .8% less oil. Is this even something to worry about? When doing such short oil change intervals, less than a percent loss of oil? That's negligible at best in my opinion when these engines hold a ton of oil to begin with.
Again I’m asking “Why the 5w40 or the 5w50?” What is the actual reasoning behind this? If you’ve had a failure of an engine, was it due to the oil? There are several factors that go into why an engine could fail. Typically, I’ve seen on S65 and S62 engines that going with a lower viscosity meant potentially not having that hydrodynamic layer under higher pressures leading to bearing failure. Now those engines have really tight tolerances. Does the S63T4 suffer from this same issue? I know they have changed materials used within, not knowing exactly if the bearings are the same? if the clearances change? not too sure...I’ve not read at all about bearings being an issue, or cylinders walls being eaten away due to lack of that lubrication…Keep in mind the S63T4 has one oil pump, a suction pump, and 16 oil spray nozzles. I highly doubt lubrication is an issue, and when keeping in mind viscosity, a lower viscosity means a better flowing oil. If the engines were indeed designed for 5w30, then going with a higher viscosity means the oil pumps work harder by nature. I need more confirmation on this, as I’m getting contradicting information. Euro vs US, etc ,etc. I know Euro emission regulations are much more stringent, then here in the US. With things like OPF making there way even into M cars now. So not sure why a 40 weight would be recommended there vs. a 30 weight here? I’ve only really seen higher weights used if per-say you add more power than the engine was initially designed for as now you’re putting more pressure on the bearings than intended, or your engines tolerances are worn to the point where a thicker oil is now needed. When talking about a stock engine, why deter from the recommended? Is the recommended a lie? And who could answer this?
In the end I’m just trying to understand these engines better, if by going 5w30 I made a mistake, then so be it. It’s a learning process and I’m all for that, but I highly doubt this would lead to any sort of engine failure due to that. The oils in a 3-5K mile change interval aren’t even in the engine long enough to degrade to a point of damage. Especially since I don’t track the car. What’re your thoughts? Anyone have insider information on this? Engine builders, why do you use what you use? What have you seen? And can you provide some evidence to further clarify your reasoning for the weight you choose. Testing, failure diagnosis, etc., are all welcome!
Thanks everyone. I know it’s a long post, but there is a lot to talk about and I'm looking forward to having a solid, and informative conversation.
