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Everything you ever wanted to know about oil . . .
In response to several postings and e-mails,
here's a repost of Ed Hackett's discourse\
on motor oil, with tables of specs for common
brands of oil.
I trust Ed approves of this repost. He obviously
knows a great deal more about this topic than most
of us do.
Thanks, Ed.
Grant Lenahan
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.
The Data:
Listed alphabetically --- indicates the data was not avaliable
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 --- ---
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 --- ---
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 --- ---
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.
==================================================================
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)
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
wheeler.wrc.unr.edu
The Desert Research Institute
DoD #0200, WMTC, BMWRA, DIOC, Reno, NV (702)673-7380
KotLS KtoLE DotD #0003
I'm not really a chemist, I'm just one of them motorsickle
sonsabitches. __=o&o>__
900SS K100RS 501 CAMEL