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.
Again, better in what regard and to what extent? It's all meaningless
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
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.
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
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.
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
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.
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.
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
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.
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.
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.
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!
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!
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! :-)
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.
A. Sinan Unur < firstname.lastname@example.org>
(remove .invalid and reverse each component for email address)
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.
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.
Testing/experimentation IS the empirical route! Look up the meaning of
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
This would be a great experiment. When do you plan to start it? :-)
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.
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.
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
A. Sinan Unur < email@example.com>
(remove .invalid and reverse each component for email address)
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. :-)
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.