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Topic ClosedEngine oil facts - viscosity and wear testing

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billd View Drop Down
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Direct Link To This Post Topic: Engine oil facts - viscosity and wear testing
    Posted: Jun/12/2019 at 8:23am
Place holder for factual information related to engine oil viscosity or "weights" and wear resistance testing.

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

This guy has done enough testing and gathered enough information from research around the world to also show that generally speaking - GENERALLY, not meaning ALL, but for the most part all else being equal, that most modern engines in good condition do best with 5w-30 oil. He also discusses that at length - and why the factory recommends a less ideal oil (5w-20) - that's because of CAFE rules... not because of sound engineering.

I will toss in here information I found from a test done by a university in conjunction with oil research - that the protective layer formed by zddp does not keep building - it reaches a point and stops. That is also mentioned here in 540rat's blog. So more isn't better - in fact more can be worse!! and adding additives to a good oil can turn it into a bad oil.

If you don't like to read - here are some important highlights from the blog by an ENGINEER and member of SAE, ASME and so on but the link above has it all - a long read, takes a while to get through, but he knows his stuff - it's not "a buddy of mine blew a cam and he did this so obviously this is better" BS that gets tossed around a lot - that sort of talk isn't proof of anything, it's not a test and it's not scientific at all. It's tossing stuff to see what sticks. 

Credentals - 
Mechanical Engineer

U.S. Patent Holder – For a mechanical device designed for Military Jet Aircraft. And two more Patents are pending, for breakthrough mechanical designs for both Military and Commercial aircraft.

Member SAE (Society of Automotive Engineers)

Member ASME (American Society of Mechanical Engineers)

Lifelong Gear Head, Mechanic, Hotrodder, Drag Racer, and Engine Builder
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THE SINGLE MOST IMPORTANT thing a motor oil does for your engine, is prevent wear. Everything else it does for your engine, comes AFTER that. But, I have found that there is a tremendous amount of misinformation and misunderstanding about motor oil. The worst of all is that a lot of people, even those at Cam Companies, blindly accept the MYTH about needing high levels of zinc in motor oil in order to have sufficient wear protection. But, that line of thinking is NOT based on technical fact, and is simply FALSE. So, at the beginning of 2012, I began Tribology Research using motor oil “Wear Testing” equipment, to explore the facts regarding the wear prevention capabilities of motor oil. For those not familiar with the terminology, Tribology means the study of friction, lubrication, and wear between moving surfaces.

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A high level of zinc/phos is simply no guarantee of providing sufficient wear protection. And to make matters even worse, excessively high levels of zinc/phos can actually “cause” DAMAGE your engine, rather than “prevent” it. Motor Oil Industry testing has found that motor oils with more than 1,400 ppm ZDDP, INCREASED long-term wear. And it was also found that motor oils with more than 2,000 ppm ZDDP started attacking the grain boundaries in the iron, resulting in camshaft spalling (pitting and flaking). The ZDDP value is simply the average of the zinc and the phosphorus values, then rounded down to the nearest 100 ppm (parts per million).

For example, if oil “A” has a 110,000 psi “load carrying capacity/film strength” (no matter how much zinc is present) in this test, and oil “B” has only a 65,000 psi “load carrying capacity/film strength” (no matter how much zinc is present) in this test, it’s not hard to understand the fact that oil “A” with its WHOPPING 70% HIGHER CAPABILITY, will provide a MUCH HIGHER level of reserve wear protection in a running engine as well (no matter how much zinc is present)

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From those failures where I was able to find out what specific oils were used, it turned out that those were oils I had already performed my Engineering Wear Protection Capability tests on. And all those oils had only provided poor wear protection capability, meaning that if they had looked at my test data before using those oils, they would have known in advance that their engines would be at significant risk of failure with those oils. And that is just what happened. 
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A number of people who have had those failures, and some had repeated failures, have contacted me, asking what they can do to prevent that failure in the future. I tell them to forget all that high zinc nonsense and look at my Wear Protection Ranking List. And to select any high ranking oil there, no matter how much zinc it has, because zinc quantity simply does NOT matter. The only thing that matters regarding wear protection, is the psi value each oil can produce in my testing. The higher the psi value, the better the wear protection. I recommend they use the SAME highly ranked oil for break-in and after break-in. It’s that simple.
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WHEN PEOPLE HAVE TAKEN THAT ADVICE, NOT ONE PERSON HAS EVER COME BACK TO ME TO REPORT THAT MY RANKING LIST DID NOT WORK FOR THEM. Since my ranking list has worked in every case to prevent wiped flat tappet lobes and lifters, it can also work for you to provide the best possible wear protection for your engine. My test data is the real deal, it exactly matches real world experience, and it is the best and most complete motor oil comparison data you will ever find anywhere.
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And for those people who have been able to use various high zinc oils without having trouble with their flat tappet engines, that only means that the oil they used had enough wear protection capability for the loads their engines saw at that time. It does not mean they were necessarily using a great oil. And it does not provide any information about how much reserve wear protection capability their oil provided, nor how their oil compares to other oils on the market.

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In addition to that, my oil test data has also been validated and backed-up by a total of FOUR other independent Industry sources. They are as follows:
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1. Well known and respected Engineer and Tech Author David Vizard, whose own test data, largely based on real world engine dyno testing, has concluded that more zinc in motor oil can be damaging, more zinc does NOT provide today’s best wear protection, and that using zinc as the primary anti-wear component, is outdated technology.
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2. The GM Oil Report titled, “Oil Myths from GM Techlink”, concluded that high levels of zinc are damaging and that more zinc does NOT provide more wear protection.
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3. A motor oil research article written by Ed Hackett titled, “More than you ever wanted to know about Motor Oil”, concluded that more zinc does NOT provide more wear protection, it only provides longer wear protection.
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4. This from the Brad Penn Oil Company:
There is such a thing as too much ZDDP. ZDDP is surface aggressive, and too much can be a detriment. ZDDP fights for the surface, blocking other additive performance. Acids generated due to excessive ZDDP contact will “tie-up” detergents thus encouraging corrosive wear. ZDDP effectiveness plateaus, more does NOT translate into more protection. Only so much is utilized. We don’t need to saturate our oil with ZDDP.

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Wear protection is determined only by the base oil and its additive package “as a whole”, and NOT just by how much zinc is present. There is nothing magical or sacred about zinc. It is just one of a number of motor oil additive package components that can be used for extreme pressure anti-wear purposes. The other components that are typically Oil Company proprietary secrets, can be added to, or used in place of zinc. And most modern API SM and SN certified oils have shown in my wear testing to be quite good when it comes to providing wear protection, and have even EXCEEDED the protection provided by many high zinc oils.

So, modern low zinc oils CAN BE USED SAFELY with flat tappet cam setups, even in engines with radical cams and high spring pressures. Simply choose from the higher ranked oils on the list at the end of this write-up, and you’ll be good to go. I know people who’ve been using modern low zinc oils in High Performance flat tappet set-ups for a long time, and they’ve had no issue at all.

On a side note:
Whatever you do, DO NOT add aftermarket zinc additives to low zinc oils. Because I did testing on this exact situation and found that adding zinc to low zinc oils, ruins an oil’s chemical properties and SIGNIFICANTLY reduces its wear protection capability. The Oil Companies always say to “never add anything” to their oil.

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The use of zinc/phosphorus as the “primary” extreme pressure anti-wear components is outdated technology. Still, even the best modern low zinc/phos oils still use a some zinc/phos, but they are used only as a “portion” of the extreme pressure anti-wear components, that make up the overall additive package. And other modern “proprietary” extreme pressure anti-wear components, which are superior to zinc/phos, and can vary from Company to Company, are used as the “primary” extreme pressure anti-wear components. But, we don’t see those components in a normal Lab test print out, because they are proprietary, so the Lab is not specifically looking for them.

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So, to find out just how much the component quantities are reduced as mileage accumulates, I also sent the Lab about a dozen used oils, both synthetic and conventional, that had 5,000 miles on them. The most noteworthy component quantity depletions among those used oils  were:

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• The zinc levels dropped by around 25% on average, over 5,000 miles. But, even with significantly reduced zinc levels, there was no reduction in the original oil film strength load carrying capability. So, that is further PROOF that the zinc level is not tied to the wear protection level.

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The test equipment used here to perform this kind of testing, focuses on an oil’s “load carrying capacity or film strength”, and for good reason. THE single most CRITICAL capability of any motor oil is its film strength. Everything else it does for your engine comes AFTER that. Here’s why. When oil is down to a very thin film, it is the last line of defense against metal to metal contact and subsequent wear or damage. And oil film strength capability DIRECTLY APPLIES to flat tappet lobe/lifter interfaces, cam gear/distributor gear interfaces, mechanical fuel pump pushrod tip/cam eccentric interfaces and other highly loaded engine component interfaces. The higher an oil’s film strength, the better your engine is protected in these areas.

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We have already discussed overly thick oils above. As for super thin oils, be aware that 5W20 motor oil came about only to slightly help improve Auto Makers’ C.A.F.E. (Corporate Average Fuel Economy) numbers. It did NOT come about to actually mechanically help the engines in any way.

Virtually any engine that calls for 5W20, can also safely use 5W30. In fact, many engines that call for 5W20 are happier, and make less mechanical noise with 5W30.

5W30 is really the optimum motor oil viscosity overall, for most water-cooled gasoline engines, including High HP engines. Any viscosity thinner than 5W30, is thinner than optimum. And any viscosity thicker than 5W30 is thicker than optimum.

Since 5W30 is really the best all around motor oil viscosity for most water-cooled gasoline engines, I personally use 5W30 in my own stock engines that call for 5W20. And I also use 5W30 in my own modified High HP engines.

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Plain bearings, such as rod and main bearings, are lubricated by oil flow, not by oil pressure. Oil pressure is NOT what keeps these parts separated. Oil pressure serves only to supply the oil to the clearance between the bearings and the crankshaft journals. Those parts are kept apart by the incompressible hydrodynamic liquid oil wedge that is formed as the liquid oil is pulled in by the spinning crankshaft. As long as sufficient oil is supplied by the necessary oil pressure mentioned above, no wear can occur. And the higher flow rate of thinner oil, supplies more oil volume to the main and rod bearings, which also helps ensure that the critical incompressible hydrodynamic liquid oil wedge is always maintained.

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Here are some comparison numbers from an 830 HP road race engine on the track:

15W50 oil = 80 psi = 265* oil sump temperature

5W20 oil = 65 psi = 240* oil sump temperature

Here you can see how the thicker oil flowed more slowly through the bearings, thus getting hotter, driving up bearing temperatures and increasing sump temperatures. And the thinner oil flowed more freely and quickly through the bearings, thus cooling and lubricating them better than thicker oil, while also reducing sump temperatures.

Here’s some additional background on all this – You might be surprised by how much heat can be generated just from an oil’s internal friction, though friction may not the best term to use here. It is probably better to think of this as the heat generated due to the shearing action taking place within the oil.

It is the shearing action of the oil between the crankshaft and bearings, while the engine is under a heavy loading condition, that generates the bearing heat that we are concerned with. The oil wedge formed as the crankshaft pulls oil in and around the clearance as it spins, is liquid oil. And since liquids cannot be compressed, the oil wedge itself is what carries that heavy engine loading (oil pressure serves only to deliver oil to the crank/bearing interface) and prevents the crankshaft and bearings from coming in contact with each other, once the engine is running. Cold start up after sitting, is when the bearings and cranksaft start out in contact with each other.

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If an engine is running hot, use a thinner oil to increase flow, increase internal component cooling, and help keep sump temperatures down. Keeping oil temps down is important to help keep oil below the threshold of thermal breakdown.

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the “specific” viscosity selected for any given engine, is very important. Engine build differences and engine wear differences, result in different clearances. And depending on how robust an oiling system is, different clearances can require different motor oil viscosities for engines to generate acceptable oil pressure. The looser the clearances, the faster a given motor oil viscosity will bleed off through those clearances. Or the thinner the viscosity, the faster the oil will bleed off through given clearances. So, we need sufficient oil pressure to ensure that an adequate oil supply is always present at critical components, to protect an engine from wear and/or damage.
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And having various motor oil viscosities available, allows us to select the correct oil for any given engine, no matter what its clearances may be. To automatically take into account all the possible variations, I recommend using the thinnest oil that will still maintain acceptable “HOT” oil pressure. And that viscosity requirement can vary from engine to engine, because of differences in clearances.
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In addition to that, the viscosity chosen may also make a difference in mechanical engine noise. Sometimes, an engine might have a little mechanical tick or rattle that isn’t really a problem, other than bothering the owner, which can be eliminated by choosing the next thicker viscosity, than oil pressure requirements alone, may have required. So, viscosity choices can give us options to meet the needs of any given engine.
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SUMMARY –  MOTOR OIL VISCOSITY SELECTION RECOMMENDATION

To provide an engine with the best “oil film strength/load carrying capability/shear resistance” wear protection during cold startup, warm-up, and normal operating temperatures – Select a HIGHLY RANKED motor oil from my Wear Protection Ranking List, that has the lowest cold viscosity rating, AND that also has the lowest hot viscosity rating, that will still maintain acceptable “HOT” oil pressure. For properly built engines, a highly ranked 5W30, will usually fulfill those requirements.

NOTE: When I talk about using thinner oil in engines as long as the oil pressure is still acceptable, I am generally referring to gas engines in Hotrods and Race cars, where any thoughts of referring a factory stock engine and its Owner’s Manual, has gone out the window, and where people tend to want to use 20W50 because they MISTAKENLY think it might be better. For those engines, there can be a significant improvement in oiling by using thinner oil than 20W50, as long as the oil pressure is still good. I say that, because a lot of those engines weren’t built with a high volume oil pump, and thin oil with a standard volume oil pump, can be asking for trouble. Thus, my comment about still needing acceptable oil pressure, in order to safely run thin oil in those engines.

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In recent years there have been entirely too many wiped cam lobes and ruined lifter failures in traditional American flat tappet engines, even though a variety of well respected brand name parts were typically used. These failures involved people using various high zinc oils, various high zinc Break-In oils, various Diesel oils, and various oils with aftermarket zinc additives added to the oil. They believed that any high zinc oil concoction is all they needed for wear protection during flat tappet engine break-in and after break-in. But, all of those failures have proven over and over again, that their belief in high zinc was nothing more than a MYTH, just as my test data has shown.

.
A high level of zinc/phos is simply no guarantee of providing sufficient wear protection. And to make matters even worse, excessively high levels of zinc/phos can actually “cause” DAMAGE your engine, rather than “prevent” it. Motor Oil Industry testing has found that motor oils with more than 1,400 ppm ZDDP, INCREASED long-term wear. And it was also found that motor oils with more than 2,000 ppm ZDDP started attacking the grain boundaries in the iron, resulting in camshaft spalling (pitting and flaking). The ZDDP value is simply the average of the zinc and the phosphorus values, then rounded down to the nearest 100 ppm (parts per million).

For example, if oil “A” has a 110,000 psi “load carrying capacity/film strength” (no matter how much zinc is present) in this test, and oil “B” has only a 65,000 psi “load carrying capacity/film strength” (no matter how much zinc is present) in this test, it’s not hard to understand the fact that oil “A” with its WHOPPING 70% HIGHER CAPABILITY, will provide a MUCH HIGHER level of reserve wear protection in a running engine as well (no matter how much zinc is present)

.
From those failures where I was able to find out what specific oils were used, it turned out that those were oils I had already performed my Engineering Wear Protection Capability tests on. And all those oils had only provided poor wear protection capability, meaning that if they had looked at my test data before using those oils, they would have known in advance that their engines would be at significant risk of failure with those oils. And that is just what happened. 
.
A number of people who have had those failures, and some had repeated failures, have contacted me, asking what they can do to prevent that failure in the future. I tell them to forget all that high zinc nonsense and look at my Wear Protection Ranking List. And to select any high ranking oil there, no matter how much zinc it has, because zinc quantity simply does NOT matter. The only thing that matters regarding wear protection, is the psi value each oil can produce in my testing. The higher the psi value, the better the wear protection. I recommend they use the SAME highly ranked oil for break-in and after break-in. It’s that simple.
.
WHEN PEOPLE HAVE TAKEN THAT ADVICE, NOT ONE PERSON HAS EVER COME BACK TO ME TO REPORT THAT MY RANKING LIST DID NOT WORK FOR THEM. Since my ranking list has worked in every case to prevent wiped flat tappet lobes and lifters, it can also work for you to provide the best possible wear protection for your engine. My test data is the real deal, it exactly matches real world experience, and it is the best and most complete motor oil comparison data you will ever find anywhere.
.
And for those people who have been able to use various high zinc oils without having trouble with their flat tappet engines, that only means that the oil they used had enough wear protection capability for the loads their engines saw at that time. It does not mean they were necessarily using a great oil. And it does not provide any information about how much reserve wear protection capability their oil provided, nor how their oil compares to other oils on the market. 
.
But, there are some high zinc oils that do provide excellent wear protection. And you can see which ones they are, by looking at my ranking list below.
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That’s why you often hear people say to break-in an engine with conventional oil, then later switch to synthetic, even though they aren’t aware that an oil being conventional or synthetic does not determine its wear protection capability.

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But, then the flat tappet guys often want to have max protection against wear to avoid wiped lobes. So, they will then often choose conventional oil with high levels of zinc, “falsely believing” that will help increase the oil’s wear protection. But, as mentioned many times before, “wear testing” and “lab testing” have ALWAYS shown that the level of zinc does NOT determine an oil’s wear protection capability.

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Thermal Breakdown BEGINS SOONER with Diesel oil, than with gas engine oils, which is not desirable for High Performance gas engine usage. And as you can see by looking at this short list of “high zinc” gas engine oils, or by looking at my complete Wear Protection Ranking List, there are many, many gas engine oils available that are FAR SUPERIOR to the best Diesel oils in terms of wear protection. Therefore, using Diesel oils in high performance gas engines is NOT the best choice, if you want superior wear protection with plenty of margin of safety (extra reserve wear protection above what the engine typically needs).



Edited by billd - Jun/12/2019 at 8:46am
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Direct Link To This Post Posted: Jun/12/2019 at 12:36pm
Oil VISCOSITY information - 

Most people are familiar with oil's viscosity rating—10W40, for example. However, very few may know that the "W" refers to "winter," not "weight." And most of us have no idea what the weight-rating numbers actually mean other than that the vehicle's manufacturer specifies a particular viscosity.
 
The viscosity of any oil changes with temperature. The higher the temperature, the lower the viscosity—the oil thins out. On the flipside, the lower the temperature, the higher the viscosity. Because of this, the Society of Automotive Engineers (SAE) has established a series of viscosity classifications that establish oil performance at 100 and 0 degrees Celsius (212 and 32 degrees Fahrenheit, respectively).
Highs & Lows
Low-viscosity oils flow better than high-viscosity ones—the lighter-weight fluid is easier to pump and therefore circulates faster through the engine's various galleries. Low-viscosity oils also maintain a lower oil pressure, but the oil pump delivers a greater volume through the galleries than it would with thicker (higher-viscosity) oils.
Heavier oils also tend to operate at higher temperatures because the oil pump has to work harder to force the lubricant through the system. Oil does not compress readily, so the added pressure increases the temperature.
In the end, high-viscosity oils maintain a higher oil pressure, but the pump delivers a smaller volume of oil.
Multigrades
Multigrade oils typically begin as base oils, such as 10W. Then viscosity-index modifiers (polymers) are added in an effort to stabilize the viscosity. This allows a 10W40 oil to flow like a 10W at cold temperatures and a 40W at higher temperatures. In other words, multigrade oils are formulated to pass viscosity tests across a range of weights. For example, 10W30 meets the requirements for 10-weight at cold temperatures and 30-weight at high temps.
The multigrade oils' viscosity modifiers are long-chain molecules that lessen the change of viscosity with temperature variance.  
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In the past, the polymer additives (used to thicken the oil) were sometimes susceptible to viscosity loss. Permanent viscosity loss occurred when high shear forces (such as the relationship between the main bearings and the crankshaft) actually break the polymer molecules into less-effective smaller pieces. On a similar note, temporary viscosity loss also occurred when the polymer molecules aligned themselves in order to create a path of least resistance.
Fortunately, today's additive packages have improved oil's shear-resistance. However, oils with the same rating from different manufacturers can exhibit different viscosity ratings in an operating engine, depending on the shear stability of their viscosity-modifying additives.
For technoids, weights are defined thusly (stokes and centistrokes are measurements of viscosity):
"SAE 30 is SAE 30 no matter what the "W" prefix number is: 0W, 5W or 10W. This viscosity in centistokes (cSt) @ 100 degrees C is with the minimum of 9.3 cSt and a maximum of 12.5 cSt.
"SAE 40 is SAE 40 no matter what the "W" prefix number is: 5W, 10W, 15W or 20W. The viscosity @ 100 degrees C is within the minim of 12.5 cSt and a maximum of 16.3 cSt.
"SAE 50 is SAE 50 no matter what the "W" prefix number is: 5W, 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 16.3 cSt and a maximum of 21.9 cSt.
"SAE 60 is SAE 60 no matter what the "W" prefix number is: 10W, 15W or 25W. The viscosity @ 100 degrees C is within the minimum of 21.9 cSt and a maximum of 26.1 cSt.
"There is no SAE 70 and no one is likely to make one with a "W" prefix number although it is possible using a synthetic base oil. This viscosity is identified as Grade 70. The viscosity @ 100 degrees C has a minimum of 26.1 cSt and no maximum."
The difference between a multigrade and a singlegrade oil: The singlegrade can't pass the low temperature viscosity test. If it did meet one of the following "W" viscosities, it would be a multigrade.
Single grade oils will become obsolete for performance engines in the future. We dropped SAE 30 and SAE 40 because SAE 10W40 does everything 30 or 40 can do—and some things the straight grades can't do—like increasing horsepower. If an off-roader doesn't like 10W40, then use 20W50. It can do everything a 10W40 can do except pass the sub-zero viscosity test at -20 degrees C.
Multigrade viscosities are run at six different sub-zero temperatures. When a racing-oil designer puts a formula together, he has to know the viscosity at 100 degrees C of every component in the additive composition. He has to have a target viscosity objective for the finished oil in each SAE grade. Once a formula is established, the technician who supervises the blending has to duplicate this formula in the correct proportions every time the product is blended. The viscosity at 100 degrees C has a plus or minus written into the oil's quality-control specification.
Multi-Viscosity
One oil manufacturer claims that "some people in the industry use multi-viscosity as if it means the same thing as multigrade. An oil cannot be multi-viscosity, but it can be multigrade by meeting the viscosity requirements for SAE 30, 40, 50 or 60 and one of the sub-zero "W" viscosity requirements.
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