And they still aren’t engineers.
Is high HTHS still important for a normal vehicle?
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Becuiase nobody still can show me any study that shows a decreased engine life in a car running xW20 vs. the 30s or 40s and that the extra protection, while factual, matters.
Too many variables going on with people driving vehicles around on a daily basis. But controlled testing shows thinner oil can cause more wear. When you extrapolating that premise it says with all other variables held constant that thicker oil (primarily oil with HTHS of around 3.0 above (gives some headroom) can reduce engine wear. Even Toyota makes a statement in their OMs that higher viscosity can add more engine protection under heavy use conditions ... those Toyota engineers must still understand Tribology.
Rings seem to take the worse beating from thinner oils.
Yes, but I'm talking about actual folks' cars. I get the data/science shows higher HTHS provides more protection. In a normal person's car that may keep it 100K and drive it "normally", I can't see how this makes any meaningful difference (i.e. breakdowns, oil consumption, other indicators of engines isssues), even if makes you feel better about it.
Like I said ... too many variables with "actual folks cars". Read what I posted again ... with all factors held constant except for the viscosity, it's shown that higher HTHS viscosity results in less wear. So if two exact engines were ran on a dyno with the same exact RPM and load profiles for the same duration, the one with thicker oil should result in less wear. There have actually been tests run (by the SwRI I think) like this on engines with irradiated parts to monitor the wear rates going in real time while the engine is running. There were a few old threads about it.
I understand all this. Oil consumption. Power. Breakdowns. Things that folks seem to more care about beyond a wear number that may not even matter w/r to the items before-mentioned.
How do you know increased wear doesn't cause more ring (which the studies show) and other components wear as well, resulting in lower compression, increased oil use, more emissions, less power, etc than an engine that has less wear at the same mileage? That's what more wear can cause, and what keeping the wear rate lower and the engine healthier than not is all about.
How do you know that the slight increase in wear has caused any issues over the life/use I described? We don't.
Define "issues". Like said before, more wear may result in worse overall engine health and performance. More wear can be caused by thinner oil in various use conditions. I'll choose to run an oil at least 3.2 HTHS (most good xW-30 oils) and of course use good maintanence (OCI & filter) to midigate increased wear. Running a oil grade higher is basically free, a no brainer for those who understand the relation between HTHS and wear.
Less wear with HTHS >= 3.2: The science backs that up - See ZeeOSix's post above with HTHS wear graph showing exponential increase of wear on the engine rings as HTHS goes below 2.6. HTHS = 2.6 is where a new 20 weight oil starts out, but it will get thinner during an oil change interval due to sheering and fuel dilution.
I think those of us who care about HTHS and MOFT film thickness really love our cars, and want to take them to 200k/300k miles. I prefer higher HTHS protection for times when I have to accelerate up inclines and engine RPM"S / engine temperatures get hotter.
I will always use a HTHS >= 3.2 5W-30 oil for any current or future car that I own.
It's a real feeling of freedom, knowing I'll never have to use oils with a lower HTHS.
I think those of us who care about HTHS and MOFT film thickness really love our cars, and want to take them to 200k/300k miles. I prefer higher HTHS protection for times when I have to accelerate up inclines and engine RPM"S / engine temperatures get hotter.
I will always use a HTHS >= 3.2 5W-30 oil for any current or future car that I own.
It's a real feeling of freedom, knowing I'll never have to use oils with a lower HTHS.
I did above:
"Oil consumption. Power. Breakdowns."
My Focus is a good example (currently my son's). 10 years/125K of ownership since new. 5W20 the entire time at 5-7.5K intervals with most if it using Motorcraft syn-blend oil and the last 20K or so on Supertech syn. No consumption. No loss of power. No breakdowns. Cheapest ownership cost vehicle I've ever owned. So if I ran 5W30, which of course as you point out in these threads ad-nausueum is fine to do, I would have less wear and therefore a healthier engine? You can't convince me that my son's car would be in any better condition that you can actually and realistically measure (the list above is about all you can do) than it is today doing it. Yes, it's a "no-brainer" that you can run a higher oil grade in this car and yes, I understand the relationship bewteen HTHS and wear.
So I don't really love my car b/c I run a 5W20 vs. a 5W30?
I prefer the engine protection of a higher HTHS 5W-30, as it cost's me $0 extra to use 5W-30 versus 5W-20.
I try to use a synthetic oil with the best additive package as well, to get the secondary protection of film strength from the additives if the film thickness fails to prevent close to metal on metal contact.
I also prefer using high mileage oils as treating the engine seals so they don't leak might be the most important thing
a motor oil can do (besides #1: protecting your engine). I am fortunate that the 4 vehicles I have don't have any oil leaks and my driveway pavement is clean.
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While it may be "nice", it's unnecessary.
I guess you have no real data about the actual condition of your focus engine either, other than its in the range of "unchanged/fine" with no noticeable issues. I agree, for most engines for most people, they aren't going to wear them out with XW20 in 200k miles so it doesn't matter much for most engines.
But the actual data collected properly says those same engines would be likely to have less wear with a higher HTHS oil. Enough to matter? No, not for most engines, but if you've got an outlier, it could make the difference between messing around with a timing chain problem in your first 100k miles or not.
It may seem to be "running great" and be all healthy from what you can tell, but how do you know it couldn't have been better than it is if xW-30 was used? Did you do some compression and cylinder leak down baseline tests, and some dyno rwhp baselines after break-in? In order to determine a difference in the real world it would take a multi-million dollar controlled test program. That's where controlled lab wear tests come in as mentioned earlier.
Sure, if the owner doesn't detect any "oil use" (lots of subjectively monitoring oil level), and the engine still "runs strong" from behind the wheel, then they believe no wear must be happening. But all engines wear, and the wear rate is caused by many factors - too low HTHS for the conditions is one of them.
Are you using low HTHS in your track car? Why not if it doesn't really matter with respect to wear? Would you put thicker oil in that Focus for track use? If not, it may not "blow-up", but it's definately going to wear faster and more.
Sure, xW-20 will work fine (with some possible increased wear) in the streets od daily driving, but even on the streets xW-30 is going to give added wear protection in all possible driving conditions. That's my whole point, I like and choose headroom.
You have summarized my stance here nicely.
For me it comes down to the fact that other than a slight fuel economy increase there is no benefit to a thinner oil, only downsides. If there was another tangible technical benefit I’d listen.
So again for me, why?
So again for me, why?
I get you dude, really...It may seem to be "running great" and be all healthy from what you can tell, but how do you know it couldn't have been better than it is if xW-30 was used? Did you do some compression and cylinder leak down baseline tests, and some dyno rwhp baselines after break-in? In order to determine a difference in the real world it would take a multi-million dollar controlled test program. That's where controlled lab wear tests come in as mentioned earlier.
Sure, if the owner doesn't detect any "oil use" (lots of subjectively monitoring oil level), and the engine still "runs strong" from behind the wheel, then they believe no wear must be happening. But all engines wear, and the wear rate is caused by many factors - too low HTHS for the conditions is one of them.
Are you using low HTHS in your track car? Why not if it doesn't really matter with respect to wear? Would you put thicker oil in that Focus for track use? If not, it may not "blow-up", but it's definately going to wear faster and more.
Sure, xW-20 will work fine (with some possible increased wear) in the streets od daily driving, but even on the streets xW-30 is going to give added wear protection in all possible driving conditions. That's my whole point, I like and choose headroom.
For my VW car I track? I run the oil based on what VW recommends which is a 502 so be definition will have the higher HTHS. I'd have no issue running a 502 5W30 as well. Would I run a 20W? Not in that car. What if I had a GTI calling for 508/0W20? For daily use sure, for track use, I'd do the 40W b/c yes, I want all the HTHS I can get when I'm pushign 270 oil temps and beating the snot out of it. That extra head room means zero (to me) driving a car around town...everyone here want to think they are severe-duty all the time when in fact, v. few are and the thinner oils are just fine in those use-cases. Run what you want clearly and if having that headroom makes you feel better, by all means! The data/science shows you have more protection.
I have considererd just running 5W30 in it b/c our Lexus uses the same oil so would be easier....but again...not necessary/doesn't make one bit of difference that anyone can measure/tell here in an econo car with 150hp driving my a 20 year old. Funny as it is tuned for a bit better driveability and maybe a few stray hp (NA car...tunes don't do much but give you a bit more agressive timing maps to take advantage of 93) and he is likely going to start auto crossing it...still...the 20W is just fine in that case.
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