smb (09/16/82)
How different are the different brands of motor oil? Are some brands really significantly better for your car than others? What about oil filters? Does anyone know of any reliable objective data on this? --Steve
rjs@hpfclo.UUCP (06/09/84)
[Blow by] I also have an oil question. Are the [expensive] synthetic oils any more/less prone to acid buildup, or is this solely a property relating to the amount of blow-by? Bob Schneider
danw@oliven.UUCP (06/15/84)
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PROBLEM: The blow-by past the rings contaminates motor oil with
sulfur compounds that oxidize raising the oil's PH (makes it acidic).
This is a chemical change , replacing the filter won't reverse
the condition. In the days of cheap oil the solution was to
change often. Modern synthetic (expensive) oils make the
'chang-er-ever-3000 mil.' solution much less attractive.
This is a non-trivial problem because if the oil becomes
acidic enough it will begin attacking the metal parts inside the engine.
There are oil analysis labs that will tell you to change the
oil if it is becoming dangerously acidic.
This is nice but avoids the basic problem , the oil isn't 'worn-out'
it is just contaminated with dilute acid
WANTED:(1) a HOME test kit to test the PH level of motor oil
and (2) a kit with chemical additives (strong BASIC chemicals) to
neutralize the acid to a safe PH level.
And replace any anti-wear-foaming-oxidizer etc additives as needed.
QUESTION: While it is certainly possible to neutralize an acid with
a base , are there technical reasons preventing the modification of
the PH of motor oil? eg will abrasive salts precipitate out of solution?
Are the necessary chemicals too toxic for use by the general public?
Have the big oil Co.s 'bought-up' the idea?
Are there any lubrication engineers out there that can shed some light
on this subject?
Does anyone make this test & additive kit?
And if so how can i get one?
THANK YOU
DAN
{hplabs|fortune|ios|tolerant|allegra|tymix}!oliven!danwvfm@ihu1h.UUCP (Vern Metzger) (06/23/84)
Some time ago I posted the following response to similar questions:
[1] Additives:
The statement about the additives in mineral (petroleum) oils and
synthetics being "essentially the same" is less accurate then
saying mineral oil is essentially the same as gasoline! I'm sure
that Mr. Carlsons friend in Detroit knows that although "some" of
the additives are the same, the quantity required and added to the
synthetic base stock is significantly less. The base stock is not
just an inert ingredient that is used to fill the can once the
"additives" have been put in. The manufacturing process,
composition quality and quantity of this element is what makes the
difference between a mineral oil and a synthetic.
The following are quoted excerpts that detail this subject.
Although it may seem lengthy, I assure you I can produce many more
articles that have documented almost identical results of their
analization and investigations.
Popular Science, April 1976
"Synthetics are `inherently' more stable, so they don't evaporate
or oxidize as easily as mineral oil. They have a `naturally'
better viscosity index. They flow freely at low temperatures, yet
don't thin out as much as mineral oils at high temperatures. Most
have multiple viscosity characteristics `without' VI improvers.
Finally, they have an excellent `natural' detergency and
dispersancy."
"What happens to the acidic wastes? Petroleum oils breakdown and
you get resins and insolubles, we've said for years that it's
necessary to drain oil periodically to get rid of the fuel-
combustion garbage. But what we've been surprised to find is that
it may not be so much the garbage as the degradation products of
the oil itself. And with these synthetics oils, there isn't much
degradation." (This last paragraph quote was by Leo Manley,
Mobils's manager of lubricants and additives)
Service Station Management, May 1980
"Refining crude oil is far cheaper than chemically engineering a
synthetic base stock. But refining also compromises the lub
characteristics of the base oil. Crude oil, as it comes from the
ground, is a soup of thousands of different "fractions." Depending
on the grade and whether it is a light or heavy crude, it might
contain everything from asphalt and waxes to light and heavy oils
to very light distillates that go into making gasoline. It also
contains sulfur and other impurities. The refining process
separates these different fractions, including those which are
capable of forming a base stock for engine lubrication.
The trouble is the refining process is an approximation so the base
stock will still contain a variety of substances, including some
impurities. There will be some fractions in the oil that thicken
at low temperatures and others that will boil off at high
temperatures over a period of time. There will also be some that
tend to oxidize and form sludge deposits. To counteract such
things the oil companies blend in various additives to improve
viscosity, oxidation and wear resistance and so on. and this is
where synthetics come out on top.
Since the man-made esters and hydrocarbons that make up synthetic
oil are extremely pure, the oil is free from the substances that
can cause thickening at cold temperatures, thinning at high
temperatures, sludge formation, etc. In other words, it's what
"isn't" in it that makes it better. This means fewer additives are
necessary, which in turn means the oil will last longer and perform
better than its conventional cousin.
Breakdown of the additives is the primary reason why oil must be
changed periodically. As the additives wear out, the oil begins to
thicken. It also loses its resistance to oxidation, sludge
formation, etc. Synthetics, however, are far less dependent on the
additives-the result being synthetics last much longer.
To illustrate the staying power of the man-made lube over Mother
Nature's blend, a standard SAE test compared the oxidation
resistance of premium quality mineral-based oil with that of a
diester-based synthetic. To pass the test, an oil must withstand
64 hours of sustained highway speed operation inside an engine.
After 40 hours, the oil can be no more than four times as thick as
it was at the beginning of the test.
After 40 hours of such punishment, the conventional oil was 121%
thicker. This compared to only 15% for the synthetic. And at the
end of the 64 hours, the conventional oil was 186% thicker compared
to only 18% for the synthetic."
To summarize all the articles I have read, a general indicator that
the condition of the oil (and the additives) would be its measured
viscosity index. The chances that a synthetic with 25,000 or more
miles on it and being within 20% of its original specified weight
are much, much greater than a conventional mineral oil with less
than 7,500 miles. A specification table contained in Pickup Van &
4WD, Dec., 1979, displayed data and test results of 23 conventional
and synthetic oils, when subjected to the 40 hour test previously
mentioned, the viscosity change of the synthetics ranged from 0%
(AMSOIL) to 30% (Love Co.), conventional 5% (Shell) to <400% (Mobil
Super). Most of the synthetics were under 6% and most of the
conventional were over 55%.
[2] Auto manufacturer support:
Granted, car manufacturers don't support the long change interval
claimed by the synthetic oil manufacturers, but they also don't say
it's not possible. There are many reasons for this, for the
consumer/buyer it means a significant increase in cost of an oil
change, availability, possibilities of confusing a special additive
oil (ex: ARCO graphite) with a true synthetic and also employing
better filtration which I have mentioned in a previous article. My
personal feeling are that they will get there, its just a matter of
time. It wasn't too many years ago that the recommended interval
was <3K miles now most are 7.5K or greater.
[3] ARCO syn question:
The statement was made that their marketing supports it but "their"
technical people don't.
Be more specific, I don't know who you know at ARCO, but they must
not work in the same department. Marketing gets their specs from
the technical people! By the way what is "ARCO syn".
[4] Meeting specs:
If, as you said, the products tested by the engineer in Detroit do
not meet the SAE SF, CC or any combination there of spec, I sure
hope he is letting the federal government and the manufacturers of
the failing products know it. In regards to the SAE specifications
SA thru SF and CA thru CD, I don't know of any automobile
manufacturer that requires a combination of both "S?" and "C?" for
a particular engine. The "S" specification is for "spark" ignition
engines and the "C" is for "compression" ignition (as in diesel)
engines. The letter following the "S" or "C" is the rating of that
product, and the higher the letter the better the product. The
current specs are SF and CD and they exceed the requirements of all
preceding ones in their same class.
Vern Metzger