dennis@vrdxhq.UUCP (R. Dennis Gibbs) (11/27/85)
There have been several requests on the net lately for information about
synthetic oil. I thought perhaps there is sufficient enough interest to
post the reply that I sent to someone who had questions on this subject.
I will try to explain my experience with synthetics, as well as all the
investigation I have done to find my information. I will try to be as ob-
jective as possible, which may be difficult at times (!).
First of all, I have used synthetics in four automobiles: 1) 1977 Datsun
210, 2) 1977 Buick Electra, 3) 1979 Datsun 310, 4) 1982 Plymouth Reliant. I
have also done extensive reading on synthetic lubricants, talked to others who
have used them, and have formed my own conclusions. Keep in mind that my ex-
perience is with Mobil 1 and Amsoil; I haven't had any experience with other
brands.
The basic problem with "regular" oil is as follows: Petroleum, no matter
how well refined, contains carbon chains of varying lengths, some short, some
long, and some in between. As petroleum oil gets hot, the shorter carbon
chains tend to boil away, leaving the longer ones behind. This causes a grad-
ual change in the viscosity of the oil. This happens especially when the oil
is under lots of pressure, which raises the temperature. This can lead to in-
creased oil consumption, and increased engine wear, especially in areas of the
engine under lots of pressure (camshafts, bearings). Another problem is
during very cold weather, the parafin content (inherently high in petroleum
oils) tends to cause the oil to become very viscous (thick). This leads to
harder cold morning starts, because the engine has to try to churn this thick
oil around when started.
Synthetics were developed originally for jet aircraft, where the problems I
mentioned above are much more critical. The synthetic base is made by pro-
ducing ("synthesizing") molecules. (I am not a chemist, so I may not be abs-
olutely correct, but this is essentially the it works). Since the base stock
is made in this manner, it allows the manufacturer to create molecules of more
consistant size (carbon chains that are mostly the same length). There are
several advantages in doing this. One, the lubricant in the final product is
more resistant to oxidation because there are fewer "smaller" carbon chains to
boil away. Also, the lubricant flows more freely in frigid weather, since the
parafin content is practically nil.
Now, the process of synthesizing the base stock is all well and good, but
there is more to this story. The process above is more expensive than refining
base stocks from crude oil from the earth. Therefore, if a manufacturer were
to compound a motor oil from a synthesized base that was "equivalent" in per-
formance to regular motor oil, it would cost more than regular motor oil. Ob-
viously, such a product would not be competetive. Therefore, manufacturers of
synthetic motor oils compound their products to far exceed the performance
levels of regular motor oils. This is the only way that synthetics can just-
ify their higher price, through greater performance.
Now to answer your questions:
1) >do engines burn/leak more of it than normal oils
No, But....It depends on the viscosity of the oils you are comparing. If
you are comparing a 5W-30 synthetic and a 20W-50 regular oil, and if the
engine in question is sensitive to viscosity in terms of oil control, then
it could be that you will burn the synthetic more rapidly than the regular
oil, because some engines simply do not have tight enough seals to enable
them to retain a thinner oil. This is a VISCOSITY related problem, and has
NOTHING to do with the fact that one oil is synthetic and the other is not.
In this case, if you compared a 5W-30 regular oil with a 20W-50 regular oil
then you would also lose the 5W-30 regular oil faster than the 20W-50
regular oil.
Assuming that the engine in question is not sensitive to viscosity, and is
in good mechanical condition, then you will not burn the synthetic as fast
as regular oil, because the synthetic is less volatile.
Another point to bring up here is: DON'T begin using a synthetic in an
engine that has over 40 or 50 thousand miles on it. By this time, engines
usually have significant deposits in them, and the greater detergency of
synthetics can lead to higher oil consumption. The best way to use a syn-
thetic is to break the engine in on regular oil for about 6-8 thousand
miles, and at that time start using the synthetic. In an older engine that
has lots of miles, the higher detergency of a synthetic can actually begin
to loosen deposits left by regular oils, which leads to the higher oil con-
sumption rate.
2) >do they really protect that much better?
I believe they do. Higher film strength, greater resistance to oxidation
(and hence viscosity change), greater resistance to viscosity change due to
temperature, higher detergency (fewer deposits), and lower coefficient of
friction are all advantages of synthetic lubricants.
The benefits of these improved properties are (compared with regular oil):
Less engine wear; increased gas mileage; easier cold morning starts; a
cleaner engine internally (fewer deposits); less frequent oil changes.
Since I am a skeptical person, I have two of my automobiles on a Spectro-
scopic oil analysis program, where I take samples of the engine oil and
have the used oil analysed. The results from such an analysis indicates
the amount (and type) of all wear metals present in the oil, the amount of
dirt in the oil, the oil's viscosity, total base number (which measures
additive depletion), and other characteristics.
In all cases, the analyses show less than average wear occuring in the
engines, and in some cases, wear is practically nil. It also indicates the
synthetic oils I use hold up extremely well, almost like new, even after
thousands of miles.
3) >can they really go long periods of time without a change (economics)
Most synthetic oils I know about claim that they can go 25 thousand miles
or one year (whichever occurs first).
Under ideal conditions, I believe this is true; however, few people drive
under ideal conditions. I prefer to split the difference and change it
twice a year, which for me is usually about 6-7 thousand miles. The oil
analysis results often indicate that I could go longer, but I like to be
conservative and change it twice a year. If I were using regular oil, I
would change it at least four times a year, (every three months) which to
me would be inconvenient. So by using synthetics I am saving two oil
changes a year for each car.
You mention economics. This is very difficult to quantify. I am certain
that the synthetics I am using give me slightly better gas mileage, but
only 2 - 3 percent better. It's really too hard to give an exact figure,
since mileage varies too much with the type of driving to be able to tell.
Another consideration: I find that cold morning starts (20 degrees F and
below), are easier. The engine turns over faster because the starter does
not have to labor against oil that is thicker than molasses. The synthetic
oils stay thinner in the frigid cold. Now, common sense tells you that if
your cold morning starts are easier, there is less wear and tear on your
battery and starter, but exactly how much of a monetary value can you place
on an easier cold morning start? This certainly should be figured in the
economics of the situation, since there are definitely benefits here, but
they are difficult to quantify.
My conclusion: I think the economic benefits are favorable (i.e., it IS
worth it), but only in the long run. The reduced engine wear benefits will
make a difference to you only if you plan to keep your car for a long time
(perhaps 80 - 100 thousand miles or more). Also, it is NOT worth it to
begin using a synthetic in a car with over 40 thousand or so miles. The
earlier you begin using a synthetic (after the break-in period), the
greater chance you will have of seeing monetary benefits sooner in the life
of the car.
4) >p.s. do you still use synthetics
You bet I do. I no longer own the 1977 Datsun 210, but I am still using it
and will continue to use it in my other three cars, and I will use it in
any other cars that I buy, as soon as the break-in period is over. As I
mentioned above, it is difficult to prove that I am coming out ahead mone-
tarily, but I am ABSOLUTELY convinced that conventional (regular) oils are
not always up to handling the punishment of today's engines. I also know
that synthetics can take punishment and continue to lubricate well where
conventional premium oil fails. You don't have to be a "race car" driver
to have driving habits that are very hard on the oil in your crankcase.
Considering the price of today's cars, and the fact that I am keeping cars
longer than I used to, I demand the finest parts and materials be used in
maintenance of my vehicles. I consider synthetic oils such as Mobil 1 and
Amsoil to be important parts of my maintenance efforts.
For more information, there are two excellent articles I would like to
point to you, one is the cover story of the April 1976 issue of Popular
Science. Also, I belive the October 1978 issue of Road and Track had an
article on synthetic lubricants. Both of these were long, informative
articles written by people with no ax to grind. Also, you may want to
write Mobil, they have been very generous with information when I have
written them.
Finally, I would like to add all the usual disclaimers: I do not work for any
company which sells or markets synthetic lubricants, nor do I benefit in any
way from the sale of synthetic lubricants.
Another final thing: I also use synthetic gear lube (from Amsoil) in the manual
transmission of my 1979 Datsun. It helped to cure some of the hard shifting I
used to have when using regular (non-synthetic) gear lube in cold weather.
Dennis Gibbs