Hello Everyone,
I just found the article I was looking for several weeks ago when the
question was ask about oil change intervals. Actually, I believe the post
was titled "Blackstone". This was back around the first or second week of
January. Anyway here is a post of the article for anyone interested. Hope
you enjoy it.
Rich - Ashburn, VA
----------------------
Thomas points out:
>There's a write up somewhere on the 'net which supports this and also shows
>that Mobil 1, Amsoil and other synthetics are better than the
>Pennzoils/Valvolines, etc...
Here it is. This was last posted to our group at least a year ago.
-tdc
* * *
All engine oils use an organic Zinc compound as an extreme
pressure/anti wear additive. Spectro adds more to their Motorcycle
oil than to the car oil because Zinc is a poison to catalytic
converters. You will also see that some "car" oil contains more
than their motorcycle oil. The difference in Zinc content between
11% and .16% is insignificant to the converter. The little data I
saw on the oils packaged by the motorcycle manufacturers indicated
that they were no better than the top automotive oils. While most
were good, they didn't offer anything the cheaper oils do. (They
are in reality just repackaged and in some cases slightly
reformulated top grade auto oils).
The following is a slightly modified repost of my original article.
I have added a few bits that address some FAQs. (long)
____________________________________________________________________
Choosing the best motor oil is a topic that comes up frequently
in discussions between motoheads, whether they are talking about
motorcycles or cars. The following article is intended to help
you make a choice based on more than the advertizing hype.
Oil companies provide data on their oils most often refered to
as "typical inspection data". This is an average of the actual
physical and a few common chemical properties of their oils. This
information is available to the public through their
distributors or by writing or calling the company directly. I
have compiled a list of the most popular, premium oils so that a ready
comparison can be made. If your favorite oil is not on the list
get the data from the distributor and use what I have as a data
base.
This article is going to look at six of the most important
properties of a motor oil readily availiable to the public: viscosity,
viscosity index (VI), flash point, pour point, % sulfated ash,
and % zinc.
Viscosity is the measure of how thick an oil is. This is
the most important property for an engine. An oil with too
low a viscosity can shear and loose film strength at high
temperatures. An oil with too high a viscosity may not pump to
the proper parts at low temperatures and the film may tear at
high rpm.
The weights given on oils are arbitrary numbers assigned by the
S.A.E. (Society of Automotive Engineers). These numbers correspond
to "real" viscosity, as measured by several accepted techniques.
These measurements are taken at specific temperatures. Oils that
fall into a certain range are designated 5, 10, 20, 30, 40, 50 by
the S.A.E. The W means the oil meets specifications for viscosity
at 0 F and is therefore suitable for Winter use.
The following chart shows the relationship of "real" viscosity to
their S.A.E. assigned numbers. The relationship of gear oils to
engine oils is also shown.
_______________________________________________________________
| |
| SAE Gear Viscosity Number |
| ________________________________________________________ |
| |75W |80W |85W| 90 | 140 | |
| |____|_____|___|______________|________________________| |
| |
| SAE Crank Case Viscosity Number |
| ____________________________ |
| |10| 20 | 30 | 40 | 50 | |
| |__|_____|____|_____|______| |
______________________________________________________________
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42
viscosity cSt @ 100 degrees C
Multi viscosity oils work like this: Polymers are added to a light
base(5W, 10W, 20W), which prevent the oil from thinning as much as
it warms up. At cold temperatures the polymers are coiled up and
allow the oil to flow as their low numbers indicate. As the oil
warms up the polymers begin to unwind into long chains that prevent
the oil from thinning as much as it normally would. The result is
that at 100 degrees C the oil has thinned only as much as the higher
viscosity number indicates.
Another way of looking at multi-vis oils is to think of a 20W-50 as
a 20 weight oil that will not thin more than a 50 weight would when hot.
Multi viscosity oils are one of the great
improvements in oils, but they should be chosen wisely. Always
use a multi grade with the narrowest span of viscosity that is
appropriate for the temperatures you are going to encounter.
The polymers can shear and burn forming deposits that can
cause ring sticking and other problems. 10W-40 and 5W-30 require a lot
of polymers(synthetics excluded) to achieve that range. This has
caused problems in diesel engines, but fewer polymers are better
for all engines. The wide viscosity range oils, in general, are
more prone to viscosity and thermal breakdown due to the high
polymer content.
Very few manufactures recommend 10W-40 any more, and some
threaten to void warranties if it is used. It was not included
in this article for that reason. 20W-50 is the same 30 point
spread, but because it starts with a heavier base it requires
less viscosity index improvers (polymers) to do the job. AMSOIL
can formulate their 10W-30 and 15W-40 with no viscosity index
improvers but uses some in the 10W-40 and 5W-30. Mobil 1 uses no
viscosity improvers in their 5W-30, and I assume the new 10W-30.
Follow your manufacturer's recommendations as to which weights are
appropriate for your vehicle.
Viscosity Index is an empirical number indicating the rate of
change in viscosity of an oil within a given temperature range.
Higher numbers indicate a low change, lower numbers indicate a
relatively large change. The higher the number the better. This
is one major property of an oil that keeps your bearings happy.
These numbers can only be compared within a viscosity range. It is
not an indication of how well the oil resists thermal breakdown.
Flash point is the temperature at which an oil gives off vapors
that can be ignited with a flame held over the oil. The lower
the flash point the greater tendancy for the oil to suffer
vaporization loss at high temperatures and to burn off on hot
cylinder walls and pistons.
The flash point can be an indicator of the quality
of the base stock used. The higher the flash point the better.
400 F is the minimum to prevent possible high consumption.
Flash point is in degrees F.
Pour point is 5 degrees F above the point at which a chilled oil
shows no movement at the surface for 5 seconds when inclined.
This measurement is especially important for oils used in the
winter. A borderline pumping temperature is given by some
manufacturers. This is the temperature at which the oil will
pump and maintain adequate oil pressure. This was not given by
a lot of the manufacturers, but seems to be about 20 degrees F above
the pour point. The lower the pour point the better. Pour point
is in degrees F.
% sulfated ash is how much solid material is left when the oil
burns. A high ash content will tend to form more sludge and
deposits in the engine. Low ash content also seems to promote
long valve life. Look for oils with a low ash content.
% zinc is the amount of zinc used as an extreme pressure, anti-
wear additive. The zinc is only used when there is actual
metal to metal contact in the engine. Hopefully the oil will do
its job and this will rarely occur, but if it does, the zinc
compounds react with the metal to prevent scuffing and wear. A
level of .11% is enough to protect an automobile engine for the
extended oil drain interval, under normal use.
Those of you with high reving, air cooled
motorcycles or turbo charged cars or bikes might want to look
at the oils with the higher zinc content. More doesn't give you
better protection, it gives you longer protection if the rate of
metal to metal contact is abnormally high. High zinc content
can lead to deposit formation and plug fouling.
Brand VI Flash Pour %ash %zinc
+ + - - +- .
20W-50
AMSOIL 136 482 -38 <.5 ---
Castrol GTX 122 440 -15 .85 .12
Exxon High Performance 119 419 -13 .70 .11
Havoline Formula 3 125 465 -30 1.0 ---
Kendall GT-1 129 390 -25 1.0 .16
Pennzoil GT Perf. 120 460 -10 .9 ---
Quaker State Dlx. 155 430 -25 .9 ---
Shell Truck Guard 130 450 -15 1.0 .15
Spectro Golden 4 174 440 -35 --- .15
Spectro Golden M.G. 174 440 -35 --- .13
Unocal 121 432 -11 .74 .12
Valvoline All Climate 125 430 -10 1.0 .11
Valvoline Turbo 140 440 -10 .99 .13
Valvoline Race 140 425 -10 1.2 .20
20W-40
Castrol Multi-Grade 110 440 -15 .85 .12
Quaker State 121 415 -15 .9 ---
15W-50
Chevron 204 415 -18 .96 .11
Mobil 1 180 430 -55 --- ---
Mobil 1 15W-50 (new) 170 470 -55 --- ---
Mystic JT8 144 420 -20 1.7 .15
15W-40
AMSOIL 135 460 -38 <.5 ---
Castrol 134 415 -15 1.3 .14
Chevron Delo 400 136 421 -27 1.0 ---
Exxon XD3 --- 417 -11 .9 .14
Exxon XD3 Extra 135 399 -11 .95 .13
Kendall GT-1 135 410 -25 1.0 .16
Mystic JT8 142 440 -20 1.7 .15
Shell Rotella w/XLA 146 410 -25 1.0 .13
Valvoline All Fleet 140 --- -10 1.0 .15
Valvoline Turbo 140 420 -10 .99 .13
10W-30
AMSOIL 142 480 -70 <.5 ---
Castrol GTX 140 415 -33 .85 .12
Chevron Supreme 150 401 -26 .96 .11
Exxon Superflo Hi Perf 135 392 -22 .70 .11
Exxon Superflo Supreme 133 400 -31 .85 .13
Havoline Formula 3 139 430 -30 1.0 ---
Kendall GT-1 139 390 -25 1.0 .16
Mobil 1 --- 430 -60 --- ---
Mobil 1 10W-30(new) 160 450 -65 --- ---
Pennzoil PLZ Turbo 140 410 -27 1.0 ---
Quaker State 156 410 -30 .9 ---
Shell Fire and Ice 155 410 -35 .9 .12
Shell Super 2000 155 410 -35 1.0 .13
Shell Truck Guard 155 405 -35 1.0 .15
Spectro Golden M.G. 175 405 -40 --- ---
Unocal Super 153 428 -33 .92 .12
Valvoline All Climate 130 410 -26 1.0 .11
Valvoline Turbo 135 410 -26 .99 .13
Valvoline Race 130 410 -26 1.2 .20
5W-30
AMSOIL 168 480 -76 <.5 ---
Castrol GTX 156 400 -35 .80 .12
Chevron Supreme 202? 354 -46 .96 .11
Exxon Superflow HP 148 392 -22 .70 .11
Havoline Formula 3 158 420 -40 1.0 ---
Mobil 1 150 430 -65 --- ---
Mobil 1 5W-30 (new) 165 445 -65 --- ---
Mystic JT8 161 390 -25 .95 .1
Quaker State 165 405 -35 .9 ---
Shell Fire and Ice 167 405 -35 .9 .12
Unocal 151 414 -33 .81 .12
Valvoline All Climate 135 405 -40 1.0 .11
Valvoline Turbo 158 405 -40 .99 .13
All of the oils above meet current SG/CD ratings and all
vehicle manufacture's warranty requirements in the proper viscosity.
All are "good enough", but those with the better numbers are icing on
the cake. The more expensive synthetics; AMSOIL, Mobil 1,
and Spectro offer the only truly significant differences, due
to their superior high temperature oxidation resistance, high film
strength, very low tendancy to form deposits,
stable viscosity base, and low temperature flow characteristics.
Synthetics are superior lubricants compared to
traditional petroleum oils. You will have to decide if their high
cost is justifed in your application.
The extended oil drain intervals given by the vehicle manufacturers
(typically 7500 miles) and synthetic oil companies(up to 25,000 miles)
are for what is called normal service. Normal service is
defined as the engine at normal operating temperature, at
highway speeds, and in a dust free environment. Stop and go,
city driving, trips of less than 10 miles, or exterme heat or cold puts
the oil change interval into the severe service category, which is
3000 miles for most vehicles. Synthetics can be run two to three
times the mileage of petroleum oils with no problems. They do not
react to combustion and combustion by-products to the extent that
the dead dinosaur juice does. The longer drain intervals possible
help take the bite out of the higher cost of the synthetics.
If your car or bike is still under warranty you will have
to stick to the recommended drain intervals. These are set for
petroleum oils and the manufacturers make no official allowance for
the use of synthetics.
Oil additives should not be used. The oil companies have gone
to great lengths to develop an additive package that meets the
vehicle's requirements. Some of these additives are synergistic,
that is the effect of two additives together is greater than the effect
of each acting separately. If you add anything to the oil you may
upset this balance and prevent the oil from performing to
specification.
The numbers above are not, by any means, all there is to determining
what makes a top quality oil.
The exact base stock used, the type, quality, and
quantity of additives used are very important.
The given data combined with the manufacturer's
claims, your personal experience, and the reputation of the oil
among others who use it should help you make an informed choice.
Ed Hackett The Desert Research Institute
edh@wheeler.wrc.unr.edu Reno, Nevada (702) 673-7380
----------------------------------------------------------------------------
--- I just recieved this data from our local oil distributor. It is the update on the new Mobil 1 formulation and that for the new Castrol Syntec. They did not have the numbers for the new Valvoline synthetics yet. The data on the new Mobil 1 is pretty impressive. Based on these numbers, price, and availiability, there is little need to look further for a synthetic oil.The Syntec seems to be compromised by it's wide viscosity range. Notice that the pour point is for all practical purposes, no better than the Mobil 1 15W-50. (actually, it's not as good) While, meeting the viscosity parmeters, the wide range is probably for marketing purposes. The Mobil 1 15W-50 will pump at -35 degrees F, which is as good as some conventinal 5W-30 oils.
Any of the ester based synthetics (AMSOIL, Mobil 1, and Syntec), will give you the benefits that Castrol is making a big deal of in their advertising. The ability to cling to metal walls is due to the polar nature of the ester base stock, not something unique to Castrol's formulation.
The Data: (add to your current article) + means the higher the better, - means the lower the better Brand and Weight VI Flash Pour %ash %zinc + + - - Syntec 5W-50 180 437 -49 1.2 0.10
Mobil 1 5W-30 165 445 -65 --- --- 10W-30 160 450 -65 --- --- 15W-50 170 470 -55 --- ---
Ed Hackett edh@wheeler.wrc.unr.edu The Desert Research Institute DoD #0200 WMTC BMWRA DIOC Reno, Nevada (702) 673-7380
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