Automotive Longevity. How Long Will it Last

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I have been leasurely reading articles on the aspects effecting gasoline engine longevity. I am only looking at engines that have no particular problems in design. In the past I would have said that the limiting step would be the rings. As the aged engine wears compression lessens. Now it seems that engines are designed in such a way that all parts have about the same longevity under normal use. Interestingly the vehicle size is not important as the smallest car or largest SUV will have about the same like span (if well kept). Engine displacement and the number of cylinders is not a factor as far as I can tell.

Living in extremely cold and hot environments, especially hot and dusty locations is very important. Cold environment wear goes along with the thought that most engine wear occurs before the oil is fully up to operating temperature. Many dispute this but the evidence is overwhelming to me including SAE papers on the topic. It concerns me enough that the start up oil viscosity at 75 F is the most important criteria that I look for when selecting a viscosity range.

Others will argue that as I live in tropical Florida I could be running straight, non multigrade oils without concern. And that I could run 40, 50 or even 60 grade oils and expect less wear with each thicker grade. I always use the multigrade oil that best matches my engines operational needs, most often thinner oils. And I have shown that the wear as measured in oil analysis is normal or below normal despite using what some would claim could only ruin my engines.

A prominent recurring theme was engine cleanliness. And maybe this is the most important. Keeping the oil and incoming air clean is the most commonly mentioned item. This goes against the grain in many ways. People are going 10,000 and 20,000 miles on their oil using brands advocating this behavior. And many will tell you that leaving the oil and air filters in longer actually makes them better. They say the dirt will eventually fill the large pores and only the better filtering smaller holes will remain. I would have thought this. Yet the analysis of oil tests has led me to change the air filter twice as often as called for in the owners manual. I believe the air filtration is more important than oil filtration. And though I do not live in a dusty environment there is certainly more dust in the air at this hot tropical location.

Sump temperature. This is also a recurring theme. While bursts of throttle will not heat up the sump a constant high load will do so. Towing big loads up mountains in mid summer will hurt. It will not cause catastrophic wear but rather accelerated wear. That is to say more wear than usual. In general things that run hotter wear more. It begs the question. Under normal loads thicker oils run hotter. Would you be better off using a thinner oil and run cooler as I always do? Wear analysis in my engines support this theory.

I am currently running another 3 year experiment to test this theory again. In the 812 Superfast I will soon analyze the 5W-40 Ferrari spec’ed oil. Then I will run a 0W-30, then maybe a 0W-20. The final leg will be the original oil and viscosity. In all unfairness I will not be taxing the oils the same. I have always waited for the thicker oils to come up to full temperature before running around the town with bursts to redline. Currently 170 - 175 F to 9,000 RPM.

I have always run the thinner oils up to full RPM before reaching stable operating temperatures. Currently the Ferrari oil has a viscosity of 80 cSt at 104 F whereas the 20 grade RLI oil I may be using (and used in other high performance cars) has a viscosity of 44 at 104 F. The hypothesis is that cooler running high RPM engines last longer than hotter running engines, despite using thinner oils.

ali
 
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And many will tell you that leaving the oil and air filters in longer actually makes them better. They say the dirt will eventually fill the large pores and only the better filtering smaller holes will remain. I would have thought this. Yet the analysis of oil tests has led me to change the air filter twice as often as called for in the owners manual. I believe the air filtration is more important than oil filtration. And though I do not live in a dusty environment there is certainly more dust in the air at this hot tropical location.
Typically, oil filters lose efficiency as they load up and the delta-p increases. Air filters and oil filters act differently as they load up with debris. Most people don't believe that, but it's been shown during ISO efficiency testing in this thread where the data can be seen. Read the linked thread from this post forward - LINK

Towing big loads up mountains in mid summer will hurt. It will not cause catastrophic wear but rather accelerated wear. That is to say more wear than usual. In general things that run hotter wear more. It begs the question. Under normal loads thicker oils run hotter. Would you be better off using a thinner oil and run cooler as I always do? Wear analysis in my engines support this theory.
Because when an engine is pushed hard, the oil temperature increases and thins out, and if the viscosity (HTHS) becomes too low then the MOFT decreases to the point of metal-to-metal contact, and wear starts to happen and can only be mitigated by the AW/AF additives (the "film strength" of the oil).

Obviously, the cooler you can keep the oil, the thinner the viscosity you can run. What ultimately matters is the actual HTHS viscosity under the actual running conditions. Thinner oils typically have lower HTHS, and therefore have less MOFT headroom to protect the engine as the oil temperature becomes higher and higher. No car manufacture will recommend a thinner oil for track use ... for a reason.
 
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Currently about 2,000. But the previous oil change was at around 800 miles.

ali
Wouldn't it be better to do this test after the engine has more miles on it, so the results aren't possibly skewed with break in metals in any way? Or is that something that doesn't matter with a Ferrari engine?
 

AEHaas

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Actually Ferrari breaks in the engine on the bench before installation at least in part. They know people are going to wing them out from the start. But certainly there will be a component of break in yet to go. They also road test every car. They usually have 40 to 60 miles on them when you take delivery.

But the last test is going back to the "thicker" oil. It will be tested after most or all the break in has been done with the thinner oils. So if anything the results will be skewed in favor of the last oil used. I will be testing the same "Ferrari" oil now and last.

Ali
 
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Actually Ferrari breaks in the engine on the bench before installation at least in part. They know people are going to wing them out from the start. But certainly there will be a component of break in yet to go. They also road test every car. They usually have 40 to 60 miles on them when you take delivery.

But the last test is going back to the "thicker" oil. It will be tested after most or all the break in has been done with the thinner oils. So if anything the results will be skewed in favor of the last oil used. I will be testing the same "Ferrari" oil now and last.

Ali
You trust Ferrari to think about how the car will be driven, but you don’t trust their oil recommendation? 🤔
 
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Sounds like this car needs a trip across the USA coast to coast and back - get more like 5000+ miles on it, then start the "test". Controlled engine wear studies (using irradiated parts for wear measurement accuracy that a simple UOA can't ever do) show that more wear occurs in some engine components as oil HTHS hits around 2.6 cP (typical xxW-20 HTHS) and below. Also, engine wear studies show that the cleaner the oil is kept, the less wear occurs. Not one study has ever shown that dirtier oil doesn't cause more engine wear.
 
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Sounds like this car needs a trip across the USA coast to coast and back - get more like 5000+ miles on it, then start the "test". Controlled engine wear studies (using irradiated parts for wear measurement accuracy that a simple UOA can't ever do) show that more wear occurs in some engine components as oil HTHS hits around 2.6 cP (typical xxW-20 HTHS) and below. Also, engine wear studies show that the cleaner the oil is kept, the less wear occurs. Not one study has ever shown that dirtier oil doesn't cause more engine wear.
I was thinking more like 10K miles. ;)
 

AEHaas

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Sounds like this car needs a trip across the USA coast to coast and back - get more like 5000+ miles on it, then start the "test". Controlled engine wear studies (using irradiated parts for wear measurement accuracy that a simple UOA can't ever do) show that more wear occurs in some engine components as oil HTHS hits around 2.6 cP (typical xxW-20 HTHS) and below. Also, engine wear studies show that the cleaner the oil is kept, the less wear occurs. Not one study has ever shown that dirtier oil doesn't cause more engine wear.
Agreed and thank you.

Though those radiation based studies, some of which I was involved with, are relatively old now and oils are better.

ali
 
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Agreed and thank you.

Though those radiation based studies, some of which I was involved with, are relatively old now and oils are better.

ali
Doesn't mean that viscosity is any less important today, unless you want to rely way more on AW/AF additives - which IMO, isn't the best way to control wear. Pretty much every article written by oil experts will say that the first line of defense to engine wear is the oil viscosity ("film thickness" = MOFT), followed by the oil "film strength" (AW/AF additives).

Viscosity is viscosity ... where oils have gotten better is in the additive package, which includes the AW/AF package that makes up the film strength to help mitigate wear when the film thickness breaks down.
 

AEHaas

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...And since the metallic asperities have been reduced from better production methods the limiting factor on wear is dirt. If the foreign matter was nil the asymptotic relation of an oil layer would prevent contact regardless of the thickness? Hence the importance of clean oil, best achieved by frequent oil changes.

ali
 

dnewton3

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I am curious, Dr Haas, how you will judge the "longevity" of the engine from your testing? I'm a statistical process quality control engineer by trade. I question your ability to make any sound conclusions from your experiments with such short durations, uncontrolled variables, and minimal data points. Your conclusions will be anecdotal at best. That does not take away from the fun and joy of doing so, but I caution you and others not to attach too much (if any) creedence to the results.

As I had before, I question your rationale of changing air filters 2x more than required. I don't know that anyone has advocated for blindly running really long FCIs for air filters. But I trust the data from Parker, Fram and others which our member Jim Allen gleaned in his research and expounded upon in his published article (see below) a few years ago; that air filters pass the vast majority of the total particulate they will ever pass in the first 10% of their lifecycle. Hence, changing filters 2x the OEM recommendation (which is probably already more often than necessary) will only increase the net amount of particulate passed into the engine. I quote the article: "This is why early or overly frequent filter changes are not advised because, according to Wake, 90 percent of the lifetime amount of dirt that passes through a filter does so in the first 10 percent of use."

There are some studies (SAE and other; below) which show that longer OCIs are beneficial in terms of wear rates. SAE study by Ford/Conoco (2007-01-4133) shows that longer OCIs can reduce the rate of wear. Before anyone lamblasts this as heresy, I suggest they purchase and read the SAE article. Further, macro data study from thousands and thousands of UOAs echos this very same thing; longer OCIs (up to 15k miles) results in less engine wear overall. There are many conditions which need to be monitored when doing this, but it's sound and proven. This is why we're seeing more and more OEMs use their (still conservative) IOLM strategy and not the age-old "3 month / 3k mile" mantra. Data is speaking to those who would listen.

The relationship between clean air, soot loading, TCB, lube filtration efficiency and OCI duration is a VERY complex one. Too many people here want to single it out to one thing, but the reality is that the variability in any one of these causes different resulting reactions in the others.

Engine "longevity" (aka wear) is affected by several things ...
- lube cleanliness levels
- air intake cleanliness levels
- duration of use of lubricant
- tribochemical barrier
- engine design improvements and flaws
- engine manufacturing improvements and flaws
- operational conditions
- environmental conditions
There are so many inputs contributing to the output that it's incredibly hard to say anyone knows for 100% sure what the singular perfect answer is. In fact, I believe it's impossible to claim so, because of the variability of all those inputs. But what we can do is discern levels of improvements which raise the overall data group performance in a statically significant manner (or not, which indicates the hypothesis is proven incorrect).



Here's Jim's article for you to read: https://www.trailerlife.com/tech/diy/the-truth-about-engine-air-filtration/
Here's my article for you to read: https://bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/
Here's the SAE article for you to read: https://www.sae.org/publications/technical-papers/content/2007-01-4133/
 
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