Mobil 1 5W-20

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Matt Whiting wrote:


Unfortunately, without knowing the scale of the bar grapha, a 2X difference is meaningless. To make an analogy, an amplifier with .002% total harmonic distortion has 2X as much as one with .001%, but neither is audible. In practical terms, it makes no difference. Perhaps the oil study is different, but we have no way of knowing that.

True.
Again, better in what regard and to what extent? It's all meaningless without context.

I don't expect you to remember, but if you had the information handy, I would believe you.

Agreed. "How" matters. How long you intend to keep it doesn't.

You're making some ENORMOUS assumptions! I'll bet there was NOTHING in the study you refer to that pointed to such a conclusion. The differences in wear - if there are any at all - are more likely on the order of a percentage point or less. To think that any oil is going to reduce engine wear by half is laughable. If such a product existed, it would be a revolutionary breakthrough and everybody would be clammoring for it.

As you suggested, do a Google search. The data is out there.

Look it up. The data is out there.

Are they using identical engines? If not, you can't make a direct comparison. What other variables are there? To draw any conclusion, you have to control the test parameters and only change one variable at a time. That's the basis of the scientific method.
If you use impirical examples instead of controlled test data, it's possible to come up with all kinds of conclusions.

It's out there, if you look.
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Brian Nystrom wrote:

I do as I read the study. And I gave you a direct reference as to where to obtain a copy if you are really interested in further educating yourself. However, you seem happy using cheap oils and if you are happy then that is all that matters, right?

Again, I showed you where to get the full article with the context and assumptions they made, who made the tests, etc.

How long in time doesn't matter much, but I meant how long as in how many miles driven.

Yes, I was making a hypothetical argument to show how the number of miles driven is directly related to whether different wear rates matter. You had suggested that the amount of miles driven didn't matter, I was showing that it matters greatly if the wear rates are different. I have no data to show if the wear rates are different. And often engines don't fail from wear per se, they fail from the rings getting stuck due to varnish and carbon build-up, oil passages getting blocked with crud, etc. I have seen enough engines torn down to know that synthetic oil keeps an engine a LOT cleaner than dino oil.

I have and I've not found anything other than AMSOIL sales pitches and other questionable "data." I gave you a direct reference to my source. If you have a source, which I doubt at this point, I'd appreciate you returning the favor.

I've never seen any data. Lots of conjecture, but nothing even approaching data. And I've personal experience that suggests this isn't necessarily the case.

Not identical, as the trainer engines are smaller, typically 200 cubic inches whereas most other singles are 360 cubes or larger. However, the engine designs are virtually identical within a family (Lycoming or Continental).

Test data is an empirical result. You may wish to refresh your memory on the meaning of empirical. I've never heard of impirical and don't believe that to even be a word.

I have. If you had data, it wouldn't be hard to cut and paste a link. I'm guessing you don't.
Matt
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Matt Whiting wrote:

I checked the MCN archives and the test appears to have been done in 2000, which is before the latests API specs came out and before Supertech Synthetic was available. While it might be worthwhile as a comparative study, it doesn't tell us much about current products.

I know that and that's what I meant when I said it doesn't matter. ANY oil will protect your car long term if it's changed at recommended intervals and you use a decent filter. I don't care how much or how little you spend on oil, as long as you use an API certified oil, it will do the job. API specs are very exacting and effectively limit the amount of variation that's possible in oils. That's the whole point of the certification.

If the argument was completely bogus, what's the point? Exaggeration like that is deliberately misleading. I can make up all kinds of "what if" scenarios too. For example, what if the actual difference in wear rate was 0.1%, which is probably closer to the truth?

Only in your world of exaggerated wear rates.

No kidding.

That I can agree with.

Then it's an apples to oranges comparison and it's largely pointless.

Sorry, I meant anecdotal.

OK, it was a typo. So shoot me.

Fine, but we all know how unreliable anecdotal data can be.
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Brian Nystrom wrote:

2000 sounds about right. I knew it was a few years ago. I'd be happy to have more current data, but I've been unable to find any.

No, the point of most certifications, and I believe API falls into this category, is to provide MINIMUM standards. It doesn't prevent a manufacturer from going ABOVE the standards and many manufacturers do this. Sure, many will skirt just above the minimums, but the MCN test showed that many of the reputable names, Mobil being one, have products that are well above the minimum requirements. So, certification doesn't limit variability, it just places a lower limit on the variability range. The upper end is generally not limited by specification.

No, in any difference of wear rate. If the rate of wear is different AT ALL, then the amount of wear between two oils will be completely dependent on the mileage driven.

Yes, my data is just as good as yours claiming that Supertech is a good oil. :-)

So now you agree that better oils are better for your engine? I thought you were saying that all oils were essentially equal and thus buying a better oil was a waste of money.
Matt
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wrote:

That's the best point yet.
I'm sure that many oil manufacturers have set up wear tests on actual engines over the years. Why haven't we seen the actual data from such tests? Probably because the difference in wear is so miniscule that it's not statistically significant. If it were significant, we would never hear the end of it in TV commercials.
Synthetic oil can truly be useful at temperature extremes that are rarely encountered by the average driver. I guess it is mostly bought by obsessive types that feel compelled to use the "best" at any cost. I do not mean this in a derogatory way. We all have our little obsessions at times.
--
Bob

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Bob Adkins wrote:

I actually don't think this has been done as the cost of doing so is enormous. Most makers use surrogate tests such as the much vaunted (by AMSOIL anyway) 4 ball wear test that ASTM developed. There are a few others, but I don't think there is any good evidence of strong correlation with real world results in real engines. It is simply too expensive to do this.

I find it useful be low about 20F and I encounter this for 12-16 weeks a year on average.
Matt
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Awww come on! The oil companies spend millions in ad's every year. Setting up and testing 2 engines would cost less than 1 prime time TV ad.
You could arrange tests on a fleet of rental cars for chump change. Believe me, there have been many tests. If the results were impressive and unambiguous, they would post them on the Goodyear Blimp!

Gah! You can have that cold weather man! :)
--
Bob

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Bob Adkins wrote:

Testing two engines doesn't mean squat statistically. I don't know what sample size you would need to ensure statistical significance, but I know it is a lot more than one for each condition being tested.

But you then have no idea what driving conditions each car is seeing, unless you heavily instrument each car. Again, this wouldn't be cheap. And you'd have to ensure that none of the rental customers ever added a quart of oil as that would contaminate your test.
The closest I've seen to this was a test that Consumer Reports ran with a fleet of taxis many years ago. However, as I recall, they weren't testing one oil against another, they were simply testing length of oil change intervals. I believe that changed the oil in some engines every 3,000 and some every 6,000. They then tore down the engines at something like 60,000 miles. I honestly don't remember the results now in detail, but I seem to recall their conclusion was that 6,000 mile change intervals were not a problem.
However, they admitted that this test had basically no correlation to the driving that virtually all of their subscribers engage in. These taxis ran 10 or more hours a day and rarely were shut down during the day. Also, 60,000 miles is, in my opinion, not enough mileage to even begin to gauge differences in engine wear unless something is very dramatically wrong. So even this test, which they said was very expensive, was virtually useless in the end.

I don't mind it for the most part, but as I approach 50 it is getting a little less fun each year. Then again, there is nothing like sitting in front of a wood fire with a cup of hot chocolate or coffee in hand, reading a good book, and watching the big snow flakes come down. It doesn't get much better than that!
Matt
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With a sample size of 200, all conditions average out.

Ya, I miss that part.
Here in Louisiana, I have no excuse for not being out working. :(
--
Bob

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Bob Adkins wrote:

Not necessarily. And it would be hard to cover the full range of driving conditions encountered in the USA with only 100 cars with each type of oil. However, let me know when you plan to start the test and I'll drive one of the cars for you ... no charge! :-)
Matt
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If the engines are otherwise identical, you would not need a lot more than, say, 15 tested with each kind of oil to detect a difference that is practically as well as statistically significant.
On the other hand, if we are setting up a test of engine lifetimes on different oils, the experiment may have to be run for a long time.
Sinan
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Brian Nystrom wrote:

Actually, that isn't the basis of the scientific method, at least not for sophisticated scientists. In many "real world" situations, this simply isn't possible, yet much science is still accomplished. Look up Taguchi for more information.
Matt
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You can do controlled, high-precision tests on few parts, or take the empirical route with many samples.
If it were me, I would test it on a fleet of 200 identical cars. 100 with, 100 without synthetic oil. After 100K miles, tear them all down and measure all ID's and OD's. Average them up, and there you have a valid test. Even with that many samples, you may not get a statistically significant variation between oil types.
--
Bob

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Bob Adkins wrote:

Testing/experimentation IS the empirical route! Look up the meaning of empirical...

I'd do something similar, but I'd run at least 200K miles and preferably longer. Almost anything will last 100K these days and I'm not even intested in engines that won't go at least 200K!
You'd also have to put extensive data recorders on each car to find out the driving conditions each experienced so you could try to normalize the data.
This would be a great experiment. When do you plan to start it? :-)
Matt
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No, I'm afraid my quality assurance days are over. And I'm glad of it! :-)
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Matt Whiting wrote:

Fair enough, but there are limits to how far you can stretch this before the results are meaningless. Comparing different engines under different loads, then trying to draw correlations between continuous running and frequent stops/starts seems pretty far-fetched. Results from such a test could might indicate that a more definitive test may be worthwhile, but in and of themselves they'd be largely meaningless.
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Brian Nystrom wrote:

Yes, I agree that it is very difficult and that is the reason that I believe it has never been done. A test worth doing would cost literally multiple millions of dollars and just isn't worth it to anyone.
Matt
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The height of bars can also be deceiving due to the choice of origin: If the vertical axis of the graph starts at 10 and goes to 15, the bar for 11 will be half the size of the bar for 12.
Not that I know anything about oil, but I do teach how to lie with statistics.
Sinan
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A. Sinan Unur wrote:

Thanks for the clear example. That's what I was trying to get across.
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Brian Nystrom wrote:

He's not saying at all what you were saying. I'm surprised you can't tell the difference. You are talking about a difference in the data and whether that difference is of significance. He's talking simply about the presentation of that data.
I now understand why you have such a hard time following my arguments. If you can't tell this difference, then the concepts I'm explaining won't be understandable either, so I'll stop wasting my time now. :-)
Matt
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