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This will take me multiple posts (4), but bear with me – I think it will be interesting and generate discussion.


I will summarize a very interesting post from the BITOG (oil) site. I have not modified anything that was stated. The article was apparently written primarily for cars, but should MOSTLY apply to any vehicle. The only thing that I disagree with in it is his statement that synthetic oils do not wear out since the synthetic oil molecules do not break down. The fact is that our <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com[img] /><st1:NumConv6p0 val=[/img]1</st1:NumConv6p0> of <st1:NumConv6p0 val=" /><st1:NumConv6p6 val="6.0" sch="4">6.0</st1:NumConv6p6>L engines do eventually breakdown the viscosity of synthetics. Maybe this wouldn’t be the case for true Group V synthetics (hence the reason Redline oil does not shear much in our engines), but lesser grades and “blends” of Group III and Group IV base stocks will breakdown in viscosity. This is proven.

I do not intend this to create controversy, but look forward to discussion. Many concepts presented are slightly contrary to what I have heard here and other places.

Regardless, hope this is interesting. First thing below is to reference the articles from the BITOG site.


http://ferrarichat.com/forum/faq.php?faq=haas_articles#faq_motor_oil_basics
<O</O

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=259902#Post2599 02<O></O>

 

Post <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com[img] /><st1:NumConv6p0 val=[/img]1</st1:NumConv6p0> of <st1:NumConv6p0 val=" /><st1:NumConv6p0 val="2" sch="1">2</st1:NumConv6p0> of <st1:NumConv6p0 val="4" sch="1">4</st1:NumConv6p0><O</O<O</O

AE HAAS articles summarized<O</O

The greatest confusion is because of the way motor oils are labeled. It is an old system and is confusing to many people. I know the person is confused when they say that a <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> oil is too thin for their engine because the old manual says to use <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0>. This is wrong.

More confusion occurs because people think in terms of the oil thinning when it gets hot. They think this thinning with heat is the problem with motor oil. It would be more correct to think that oil thickens when it cools to room temperature and THIS is the problem. In fact this is the problem. It is said that <st1:NumConv6p0 val="90" sch="1">90</st1:NumConv6p0> percent of engine wear occurs at startup. If we are interested in engine longevity then we should concentrate our attention at reducing engine wear at startup.

Oils are chosen by the manufacturer to give the right thickness at the normal operating temperature of the engine. I will say this average oil temperature is <st1:NumConv6p0 val="212" sch="1">212</st1:NumConv6p0> F, the boiling point of water. On the track that temperature is up to <st1:NumConv6p0 val="302" sch="1">302</st1:NumConv6p0>F. It is important to realize that these are two different operating environments and require different oils.
<O</O
The problem is that the viscosity of oil varies with its temperature. A “<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0>” weight oil has a viscosity of <st1:NumConv6p0 val="3" sch="1">3</st1:NumConv6p0> at <st1:NumConv6p0 val="302" sch="1">302</st1:NumConv6p0> F ( <st1:NumConv6p0 val="150" sch="1">150</st1:NumConv6p0> C ) and thickens to <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0> at <st1:NumConv6p0 val="212" sch="1">212</st1:NumConv6p0> F ( <st1:NumConv6p0 val="100" sch="1">100</st1:NumConv6p0> C ). It further thickens to a viscosity of <st1:NumConv6p0 val="100" sch="1">100</st1:NumConv6p0> at <st1:NumConv6p0 val="104" sch="1">104</st1:NumConv6p0> F ( <st1:NumConv6p0 val="40" sch="1">40</st1:NumConv6p0> C ) and is too thick to measure at the freezing point of <st1:NumConv6p0 val="32" sch="1">32</st1:NumConv6p0> F ( <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0> C ).<O</O

The automotive designers usually call for their engines to run at <st1:NumConv6p0 val="212" sch="1">212</st1:NumConv6p0> F oil and water temperature with an oil thickness of <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>. This is the viscosity of the oil, not the weight as labeled on the oil can.<O</O

It is time to introduce the concept of lubrication. Most believe that pressure = lubrication. This is false. Flow = lubrication. If pressure was the thing that somehow lubricated your engine then we would all be using <st1:NumConv6p0 val="90" sch="1">90</st1:NumConv6p0> weight oil. Lubrication is used to separate moving parts, to keep them from touching. There is a one to one relationship between flow and separation. If you double the flow you will double the separation pressure in a bearing. The pressure at the bearing entrance is irrelevant.<O</O

High flow does more than lubricate. It is one of the things used to cool the hottest parts of your engine, the pistons, valve areas and bearings. This cooling effect is as important as lubrication in your engine. If your engine is running hot use a thinner oil. The flow will increase and so will the cooling. This is even more important in the racing condition.<O</O

 

Post <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com[img] /><st1:NumConv6p0 val=[/img]1</st1:NumConv6p0> of <st1:NumConv6p0 val=" /><st1:NumConv6p0 val="3" sch="1">3</st1:NumConv6p0> of <st1:NumConv6p0 val="4" sch="1">4</st1:NumConv6p0>
<st1:NumConv6p0 val="4" sch="1"></st1:NumConv6p0>
<st1:NumConv6p0 val="4" sch="1">AE HAAS articles summarized - continued</st1:NumConv6p0><O</O

It is time to dispel the notion that <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> oil is too thin when our manual calls for <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0>. A <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> is always the better choice, always. The <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> is not thinner. It is the same thickness as the <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> at operating temperatures. The difference is when you turn your engine off for the night. Both oils thicken over the evening and night. They both had a thickness, a viscosity of <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0> when you got home and turned your engine off. That was the perfect thickness for engine operation.<O</O

The downside of a mineral based multigrade oil is that this VI additive wears out over time and you end up with the original straight <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0> weight oil. It will go back to being too thin when hot. It will have a thickness of <st1:NumConv6p0 val="6" sch="1">6</st1:NumConv6p0> instead of <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>.<O</O

With normal oil change intervals the VI improver will not wear out and so the problem does not really exist. In fact, oils do thin a little with use. This is partly from dilution with blow by gasoline and partly from VI improvers being used up. What is more interesting is that with further use motor oils actually thicken and this is much worse than the minimal thinning that may have occurred earlier.<O</O

Synthetic oils are a whole different story. There is no VI improver added so there is nothing to wear out. The actual oil molecules never wear out. When the additives wear out in a synthetic oil it still has the same viscosity. It will not thin as a mineral oil.
<O</O

I remind you that a <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0> or <st1:NumConv6p0 val="5" sch="1">5</st1:NumConv6p0> or <st1:NumConv6p0 val="2" sch="1">2</st1:NumConv6p0> weight oil is still too thick to provide lubrication at startup. They are all too thick at startup. There is currently no engine oil thin enough to operate correctly at startup. They all cause excessive wear at startup.<O</O

Since the synthetic oil thickens less on shutdown your startup will be easier and so will the stress on your engine. This is perhaps the best thing the synthetic class has over the mineral based oils.<O</O

Some people have said they use thicker oils because they only use their cars every <st1:NumConv6p0 val="2" sch="1">2</st1:NumConv6p0>, <st1:NumConv6p0 val="3" sch="1">3</st1:NumConv6p0> or <st1:NumConv6p0 val="4" sch="1">4</st1:NumConv6p0> weeks. They are afraid that thin oils will fall off the engine parts and result in a lack of lubrication at startup. Think about your lawn mower over the winter. I gets gummed up solid. The oil and fuel thicken over time resulting in engine failure. Anyway, oil on the surface of parts does not lubricate. It is the FLOW of oil between parts that lubricates. Thick, old, waxy oil can only be bad.
<O</O

As it turns out synthetic oils do cling to parts better as they have higher film strength than mineral oils. Synthetics are thinner overall. They have greater slipperiness. Yet they stick better to engine parts. Again, this concept is the opposite of normal thinking.<O</O
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Remember, the only difference between a <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="40" sch="1">40</st1:NumConv6p0> and a <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>W-<st1:NumConv6p0 val="40" sch="1">40</st1:NumConv6p0> is that the <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="40" sch="1">40</st1:NumConv6p0> thickens less after you turn off your engine. It is still too thick in the morning at startup but not as thick as the <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>W-<st1:NumConv6p0 val="40" sch="1">40</st1:NumConv6p0>. Yet, they are still too thick to use until they both warm up to operating temperature at which point they have the save viscosity, around <st1:NumConv6p0 val="13" sch="1">13</st1:NumConv6p0> to <st1:NumConv6p0 val="14" sch="1">14</st1:NumConv6p0>. Remember that the <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0>, <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> and straight <st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> weight oils all have a viscosity of around <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0> at normal engine operating temperatures.<O</O

 

Post <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com[img] /><st1:NumConv6p0 val=[/img]1</st1:NumConv6p0> of <st1:NumConv6p0 val=" /><st1:NumConv6p0 val="4" sch="1">4</st1:NumConv6p0> of <st1:NumConv6p0 val="4" sch="1">4</st1:NumConv6p0>
<st1:NumConv6p0 val="4" sch="1"></st1:NumConv6p0>
<st1:NumConv6p0 val="4" sch="1">AE HAAS articles summarized - continued</st1:NumConv6p0><O</O

I would like to go back to the worry that oil falls off the parts when a car is stored or sees long periods of inactivity. For the first oil change in my <st1:NumConv6p0 val="575" sch="1">575</st1:NumConv6p0> Maranello I drained the Shell and put in <st1:NumConv6p0 val="0" sch="1">0</st1:NumConv6p0>W-<st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> Mobil <st1:NumConv6p0 val="1" sch="1">1</st1:NumConv6p0>. This was at <st1:NumConv6p0 val="775" sch="1">775</st1:NumConv6p0> miles on the odometer. I drove the car home from work, put it on the lift and drained the transaxle and engine oils. I also opened and drained the oil cooler and took off every line that is in the oil system. I wanted to get every speck of the Shell oil out of there. For optimal results you are not supposed to mix synthetic oils of different brands.

The system takes <st1:NumConv6p0 val="12" sch="1">12</st1:NumConv6p0> quarts with a “normal” oil change but took <st1:NumConv6p0 val="15" sch="1">15</st1:NumConv6p0> quarts for this change. It all took about an hour. I then started the engine to check for leaks. The multitude of mechanical engine noises that followed nearly broke my eardrums for about <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0> long seconds. Then it was suddenly very quiet. You could hear a pin drop. There was certainly the most possible amount of surface oil on all the internal parts as the engine was only off for an hour. But it was not until the oil circuit primed, filled then sent flow into all the parts that any lubrication was occurring. Hence all oil filters that are manufacturer certified have back flow limiters to keep the oil filter full even with the engine off.<O</O
<O</O

Effect of Break-In and Operating Conditions on Piston Ring and Cylinder Bore Wear in SI (Spark-Ignition) Engines, Schneider et al:
The rate of wear is much higher within <st1:NumConv6p0 val="15" sch="1">15</st1:NumConv6p0>-<st1:NumConv6p0 val="20" sch="1">20</st1:NumConv6p0> minutes of start-up than after reaching normal operating temperature. There was a lot of data but I conclude that the initial start-up time period (first <st1:NumConv6p0 val="20" sch="1">20</st1:NumConv6p0> minutes) result is <st1:NumConv6p0 val="100" sch="1">100</st1:NumConv6p0> nanometers of wear whereas the steady state wear rate was only <st1:NumConv6p0 val="4" sch="1">4</st1:NumConv6p0> nanometers per hour thereafter. (Hence we should be concerned about start-up oil thickness more than running thickness. This justifies the statement that <st1:NumConv6p0 val="95" sch="1">95</st1:NumConv6p0> percent of engine wear occurs just after start-up).<O</O
<O</O

People think that taking the car out for a <st1:NumConv6p0 val="10" sch="1">10</st1:NumConv6p0> or <st1:NumConv6p0 val="15" sch="1">15</st1:NumConv6p0> minute spin will keep it in good shape. Well that is better than nothing because at least everything is splashed down with oil in the engine and some switches are activated that helps remove corrosion. But to burn off excess fuel and water from the oil it must be brought up to full operating temperature. This takes <st1:NumConv6p0 val="20" sch="1">20</st1:NumConv6p0> or <st1:NumConv6p0 val="30" sch="1">30</st1:NumConv6p0> minutes. Your coolant heats up in as little as <st1:NumConv6p0 val="2" sch="1">2</st1:NumConv6p0> – <st1:NumConv6p0 val="3" sch="1">3</st1:NumConv6p0> minutes but oil takes up to half an hour to get up to full operating temperature. You should drive the car for another half hour or more after the oil is up to temperature.

People do not realize that “severe” driving conditions that require more frequent oil changes include stop and go city driving of only <st1:NumConv6p0 val="20" sch="1">20</st1:NumConv6p0> minute drives or less. This is a severe condition because the oil never gets hot and never burns off the extra fuel or water. For this reason the oil must be changed more often.

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This concludes my "cut and paste". The full article is worth reading.

 

Hmm, this would seem to conflict with something I posted a while back about lower viscosity oils gravity draining from engine parts more than higher viscosity oils. The person who told me that is a chief scientist at Timken. He also told me that film thickness is critical to an oil's ability to lubricate reciporicating parts of an engine where entrainment velocity can go to zero, a la pistons/cylinder walls. At zero entrainment velocity, you have zero oil flow (i.e. zero elasto-hydrodynamic contribution to film thickness), and static oil film thickness (i.e., viscosity) is all there is. This is contrary to Haas's assertion that "oil on the surface of parts does not lubricate. It is the FLOW of oil between parts that lubricates."

A.E. Haas seems like a pretty smart guy, but I admit I'm skeptical about some of his info. Anyway, I'll be seeing my friend this weekend and will ask him about these posts. Stay tuned.

 

I am anxious to hear what your contact at Timken has to say! I agree that film strength MUST be important. I am just not convinced that a 15W40 mineral oil has better film strength than a synthetic 5W40 oil just because of the lower vicscosity at temperatures below operating temperatures (since film strength and viscosity are different properties). Haas made a statement that synthetics inherently have higher film strength than mineral oils - I would like to believe this, but need to see data (or hear a second opinion from an expert).

Clearly at operating temperatures a 5W40 is not "thinner" than a 15W40.....only at temps lower than operating. So why does Ford not recommend a 5W40 year round like Haas is recommending?

I do not believe the answer to this is thickness or film strength. Some say the 5W40's shear more than a 15W40 does. Maybe this is the answer, but clearly this is not true for Schaeffer or Redline. Maybe fuel dilution, soot, condensation, etc. are so much of a concern that Ford is concerned about folks using a synthetic and extending the OCI (probably justified).

Moebdick - thanks for your response. Again - I am very interested in hearing what an expert says to all these questions.

 

Sorry but this is pure crap. VI improvers are added to both dino and synthetic multigrade oils. To make a multigrade oil, dino or synthetic, you start out with a basestock weight that you want when the oil is cold (40C or 100F), ie 5 for 5W or 15 for 15W. Then you add VI improvers to get to the desired warm engine (100C or 210F) characteristics ie 40.

With a 5W-40 or 15W40 multigrade oil, when it is cold (40C or 100F) it has the characteristics of a straight weight 5 or 15 oil. When the oil is warm (100C or 210F) do to the VI improvers the oil has the characteristics of a straight 40-weight when the oil is new and clean.

The lower weight of the basestock the higher its volatility (ie lower flash point). Now if you take a like for like basestock weight, ie 15-weight synthetic and dino basestocks, generally the synthetic basestock will take less Viscosity Improvers to achieve the same 40-weight when warm, so generally the synthetic base stock is more shear stable.

A synthetic oil can be a group III basestock (highly refined dino), group IV PAO (Polyalphaolefin, usually either a 1-decene base or 1-dodecene base), or a group V POE (Polyol Ester).
Note: A 1-dodecene base PAO generally has a lower volatility than a 1-decene PAO, but at the cost of a higher pour point (10-15C). So the type of PAO basestock must be chosen based on the application.

Today most synthetic engine oils are a Group III basestock (ie Rotella, Motorcraft etc).

Mobil 1, Schaffer, Amsoil etc are group IV or group III & IV blends. Schaffer 9000 is a blend of 75% Group III & 25% Group IV.

Redline is the only commercially available Group V (PEO) synthetic available for automotive engines. PEO oils are the most heat resistant & shear stable oils available and are used extensively in jet engines do to the high heat loads experienced. They are also extremely expensive and must be formulated very carefully to play well with all the different materials in an automobile engine.

 

With a 5W-40 or 15W40 multigrade oil, when it is cold (40C or 100F) it has the characteristics of a straight weight 5 or 15 oil. When the oil is warm (100C or 210F) do to the Viscosity improvers the oil has the characteristics of a straight 40-weight when the oil is new and clean.

Generally the larger the spread between the cold weight rating and the warm weight rating the more Viscosity improvers that must be added to the base stock. Comparing a 5W-40 syn to a 15W-40 dino the amount VI improvers is fairly close. However the problem becomes when the VI improvers shear, the 15W-40 oil reverts to a 15-weight and the 5W-40 reverts to a 5-weight.

The thinner the oil base stock, the lower its film strength and lubricating properties in high load situations (ie the easier it is squeezed out). All oils are squeezed out from between the bearing surfaces under high load situations (ie acceleration), thicker oils resist being squeezed out at a higher rate than lower viscosity oils. Now to provide protection when the oil is squeezed out of the bearing area ,lubrication is dependent on the wear additives in the oil package to provide a boundary layer of protection. However, the problem is that as more zinc, phosphorous & other boundary layer additives are added to the base stock, the volatility increases and this results in oil becoming thicker (increase viscosity) with use do to the high level of oxidants in the oil. As and oil thickens it cannot flow as well, and this effects the overall lubrication qualities of the oil.

The main advantage of synthetic oil is increased flow ability at cold temperatures and higher flash points for the same weight base oils. If you operate your vehicle in extreme cold then synthetic oil has an advantage over dino.

Now as far as Schaffer 9000 & Redline DEO performance in the 6.0, these oils are as different as night and day.
The Schaffer 9000 5W-40 is a blend of 25% Group IV & 75% Group III and has a very robust anti-wear additive package. So far there are very few UOA on this oil in the 6.0, but for normal OCI it appears to hold up well. However I am not yet convinced it will hold up well to extended OCI in the 6.0.

The Redline 15W-40 DEO is a Group V (PEO) and is a superior synthetic base stock. The Redline holds up well in to extended OCI in the 6.0 for a couple of reasons, 1) it is a 15W-40 synthetic (Most other synthetic DEO are generally a 5W-40 or lower base stock viscosity), 2) Group V PEO base stock has a very high flash point (hence the reason it is used in jet engines). PEO oils perform the best in both extreme heat & cold. The down side to a PEO synthetic is its high cost and complexity in blending to safely work in automobile engines.

If I needed a synthetic oil to perform in both extreme heat & cold, then Redline would be my first choice since it is a PEO base stock. If however you need synthetic oil only for extreme cold then any of the Group III or Group IV base stock oils will work just fine and are cheaper to purchase than Redline.

For towing and high load use a thicker base stock oil is a better choice over all except in extreme cold use. Oil weight effects engine wear in several ways, and people get hung up on cold start wear. If an oil is too thin you will get increased bottom end wear do to the high load conditions on the oil at warm temps. If the oil is too thick you will get increased top end wear do to the slow flow at cold temps.

 

Blackhat -

Thanks for your time responding. Your posts answer a number of questions. Especially the way the multigrade oils are formulated - ie starting with a base stock at the lower viscosity and enhancing the performance at higher temperatures with VI (viscosity improvers) to get the multi grade performance.

I wonder why Haas made the statement about synthetics not having VI's? It seems so basic. Perhaps since his background seems to be in race cars, perhaps he was talking ONLY about Group V oils??

I also have a question on a comment from a post (copied in italics below):

"For towing and high load use a thicker base stock oil is a better choice over all except in extreme cold use. Oil weight effects engine wear in several ways, and people get hung up on cold start wear. If an oil is too thin you will get increased bottom end wear do to the high load conditions on the oil at warm temps. If the oil is too thick you will get increased top end wear do to the slow flow at cold temps."

You talk about thin and thick oils, but all of the "40W-hot" multigrades (5W40, 15W40, etc) are all 40W at operating temperature. Are you saying that at begining of life (before shear), there are no noticeable differences with these oils. As operating hours increase and shear increases, then the oils become more like their base stock and hence a 5W40 becomes thinner at operating temperature? If so, then you should be able to use oil analysis (and the measured viscosity) to decide when to change a 5W40 and essentially use it year round? Maybe at the only cost of more frequent oil changes, but no performance concerns?

I find this all very interesting, so again, I appreciate the responses, challenges, AND corrections!

 

I have no idea why he made this statement, i can only assertain he does not understand multigrade oil design and blending. Be it a dino or synthetic (PAO or PEO) Viscosity Improvers are needed to manufacture a multigrade oil. All oil basestocks are formulated with a specific single viscosity weight, then blended with additives to achieve a muiltigrade oil.

Exactly, under high load and heat the 15W-40 will provide a greater film strength & lubrication as the oil is used & sheared than a 5W-40.

In theory maybe, but a simple UOA does not tell the full story. When you are towing 12K lbs through West TX, AZ, SoCal in July or August and it is 115 in the shade you will find that the engine and oil are under extreme load. A 15W-40 will provide a larger cushion of protection than a 5W-40 run for the same number of miles. Also the Viscosity reading of the UOA alone can be mis-leading, as you also need to know the amount of Soot, insolubles, oxidation etc the oil has been subject to. Oxidation, Soot Load (high with EGR Diesel engines), heating of the oil, presence of other contaminents in the oil will all increase the Viscosity reading of the basic UOA. Initially as an oil shears down in weight the Viscosity reading is low and then the Viscosity readings rise as the oil is used for extended periods do to the contaminents in the oil.

Basic UOA is good for watching wear trends in an engine and the spotting of failures early, other uses are extrapolations at best. A thinner weight multigrade oil, ie 5W-40 is only an advantage in cold temps, and slight MPG gains do to increased flow at low temps. However under high temps and loads it is a disadvantage as the film strength is still lower and thus relies more heavily on Antiwear additives for the "boundary layer" protection.

For high temp and load conditions a heavier base stock provides better lubrication protection and is effected less by shearing. Redline DEO performs well in the 6.0 for two main reasons it is a 15W-40 and a Group V PEO. Group V PEO oils are the most robust base stocks for extreme conditions (both hot & cold). Group IV PAO base stocks do not have a significant Flash point gain over modern Group III hydrocracked dino oils. Where the Group IV PAO oils excelled in the past was when comparing them to Group I & II base stocks. Most 10W-30 multigrade oils are still made from Group I or II base stocks, hence one of the reasons they do not perform well in the 6.0 (or other motors for that matter).

If i lived in extremely cold climates, i would run either a 0W-40 or 5W-40 in the winter and a 15W-40 in the summer. You can run a 15W-40 in extreme cold but you must then run not only a block heater but also an oil pan heater as well, religiously, to prevent cold oil starvation problems at start up. Unfortunately in some operating environments it is not possible to plug your truck in all the time, so a thinner weight oil is needed.

If you do not tow/haul much and live in a climate that only gets moderately warm upper 80's to low 90's then a 5W-40 will perform fine for this use, and better than most 10W-30 oils, do to the better quality of the base stocks in the 5W-40 oil compared to the 10W-30.

 

At the risk of getting off-topic (and wading in over my head), I believe that PAOs produced from chemically pure 1-decene can have multiviscosity properties without using any viscosity index improvers. I'm pretty sure there are synthetic 0W-20 oils that fit this category. That said, VI improvers are often used to improve performance of Group IV base synthetics.

In a nutshell, i suspect this may be at the heart of Ford's rationale for not recommending 5W-40 full spectrum or for towing. They probably spec'd the oil for worst case scenario: a truck loaded to 33,000 GCWR driving full tilt through Arizona desert in the summer time.

That's changing fast, according to this article .

 

I have never seen a multiviscosity base stock in any type of oil, be it dino, PAO or PEO, this is trying to defy the basic laws of chemistry and chemical bonds to achive this. If you have a source for this type of feed stock i would like to see more info on this. To date i know that Shell, Chevron/Phillips, Exxon/Mobil, Hatco (producer of PEO base stock) have not developed a multiviscosity base stock.


Very imformative article thanks for the link. Actually 1-dodecene (C12 PAO) has been around since about 1995, the C12 has a higher flash point than 1-decene (C10 PAO) but the trade off is the cold pour point is 10-15C warmer for C12 than C10. The initial reason the 1-dodecen was produced was do to the constraints caused by a lack of raw material feedstock supplies to produce 1-decene.

C12 was initially produced to fill a gap in the C10 supply chain, but C12 was later found to have a higher flash point and is an excellent base stock to use when low pour points are not critical. So yes PAO technology continues to advance, the proper oil base stock choice hinges on the finished product requirements. Unfortunately Group IV PAO oils are still considerably more expensive than Group III base stock oils and in the majority of applications the increased cost of the PAO does not result in superior performance over Group III base stock oils. Now if you have an application that needs both extreme cold pour point and extreme high flash points in the same package, a Group V PEO base stock is needed. PEO base stocks are the oil of choice in jet engines for this reason.

PAO oils also do not blend with additives effectively so the PAO base stock must be blended with an ester co-base (usually di-ester and/or polyol ester). The additive package is soluble with ester and the ester is soluble with PAO. PAO oils cause seal shrinkage, while esters cause seal swelling so the two together offset the effects of each on seals. PEO oils have one draw back and that is do to there high natural detergency, they super clean the engine and remove all previous varnish etc. So switching and older engine (50k or more miles) to a PEO base oil can cause filter & oil passage plugging resulting in oil flow problems and starvation. Switching an older engine over must be done with care.

 

Great article! A lot to learn in these discussions!

 

OK I'm lookin...nothing yet other than marketing babble.

Meanwhile, here's a source that describes some commercially available PAOs. It's a Google books thing, so hopefully it'll display. Anyway, what it says is "The viscosity of a high VI fluid changes less dramatically with changes in temperature compared to the viscosity changes of a low VI fluid. A practical consequence of this property is that PAOs do not require viscosity index improvers (VIIs) in many applications."

 

That statment is over simplified. Yes an oil with a higher Viscosity Index (VI)is more stable all other factors being disregarded, but only tells the Viscosity/Temperature relationship between 40C - 100C. The VI index does not tell you what is going on Below 40C or above 100C. Two lubricants with the same VI may perform dramatically different at temperatures below 40C and above 100C. A C10 (1-decene) PAO has a lower VI than a C12 (1-dodecene) PAO, but the C10 is a better choice for extreme cold applications since it has a lower poor point than a C12, but the C12 has a higher flash/fire point, so is a better choice for high temp applications and longer drain interval applications. Yes most synthetic oils have a high VI index, but so do Group III dino oils.

Oil base stocks are classified at 100C (cSt) and are most commonly found in C10 = 4,6,8,10 or C12 = 5,7,9, this is an approximate viscosity range of 5 - 20 weight. You can get a C12 in 2.5 & 25 cSt as well for specific applications, and a C10 in 40 & 100 cSt. Note: 25, 40 & 100 cSt base stocks are normally used to formulate gear lubes with a 75 - 140 viscosity rating.

You can blend a 4 & 6 cSt to get a 5 cSt but the blended oil will have a lower flash/fire point and warmer pour point than a straight 5 cSt oil. This is do to having different molecular sizes in the 4-6 blend as compared to a uniform size in the straight 5 cSt base stock. All multigrade oils need Viscosity Improvers to span the weight range the oil is being designed for. Yes a 15-weight PAO will require less Viscosity Improvers than a 15-weight dino oil to achieve a 15W-40 multigrade oil and so the PAO base 15W-40 should be more shear stable than the 15W-40 dino oil. Were the problem lies is in comparing a 5W-40 syn oil to a 15W-40 dino oil, the 5W-40 syn oil has as much or more Viscosity improvers than the 15W-40 dino oil, this will result in the 5W-40 syn oil to shear as fast/faster than the 15W-40 dino oil. The problem results in the fact that under the same conditions the 5W-40 will be thinner than the 15W-40 do to Viscosity Improvers shearing because the base oils were thinner in the synthetic to begin with.

A general rule of thumb with multigrade oils, you did not want to have a span ratio greater than 3 in order to retain an oil that would resist shearing and degradation longer. When looking at older multigrade dino oils, a 10W-40 (4:1) was not as shear stable or robust as a 10W-30 (3:1). This is one reason a 10W-40 motor oil got a reputation as not being a very robust oil and a poor choice in high load applications. With DEO oils you have a 15W-40 (2.67:1) or 10W-30 (3:1) the 15W-40 has always been more robust and passes all tests, the 10W-30 has a limited use range and fails many severe test requirements. The 5W-40 syn (8:1) has a very high span ratio but part of this is offset by the fact that synthetic oils are naturally more shear stable than most dino oils do to their higher VI index. However the synthetic base stock can only help so much and still needs a high dose of Viscosity Improvers to obtain the 5W-40 span. This is why a modern 15W-40 dino oil is a better choice than a 5W-40 in high heat/load conditions.