Oil Info for Nerds Continued
Are 0W-xx oils too thin for my engine?
As discussed previously, multi-grade oils are designed to behave like two different oil weights at two different temperatures. Since an oil is thicker with colder temperatures, a lower weight oil flows better, and better protects the engine during start-up since it is easier to pump to critical areas. So, a 0W-xx oil is a better oil for start-up, especially in cold temperatures. When the oil heats up and starts to thin out, it becomes a heavier weight oil just like a 5W-xx or 10W-xx oil would. So, a 0W-xx oil is only a “thinner” oil when it’s cold- where it is a benefit. At operating temperatures, a 0W-30 is the same weight as a 5W or 10W-30, just as a 0W-40 is the same weight as a 15W-40, etc... Therefore, 0W-xx oils tend to be better suited for year-round use in any climate, since they flow better in cold temps but become as thick as any other similar grade oil when hot.
Is a thicker oil better for engine protection than a thinner one?
Not usually, but sometimes. There is a relationship between viscosity, pressure, and lubrication. As viscosity decreases, or pressure increases, lubrication begins to suffer at some point. The relationship can be plotted for various oils and the resulting graph is known as the Stribeck Curve. This curve shows us that increasing levels of pressure require an increase in viscosity in order to maintain proper lubrication. Thicker oil will have higher film strength than thinner oil, and therefore withstand extreme pressure and heat better. This is why racing engines which see extremely high temps and pressures will use very high oil weights. For a street driven car, however, too thick of an oil will create more drag in the engine and can cost you horsepower and fuel efficiency. The general rule of thumb is to use as thin an oil as possible that still offers good protection from engine wear. Nissan recommends nothing thinner than a 30 weight and nothing thicker than 40 weight oil. The only way to be sure if higher viscosity oil is needed to protect your engine for the way you drive, is with a UOA.
Why are some oils different viscosities for the same weight of oil?
As previously discussed, an oil’s hot viscosity must fall within certain limits at a specific temperature of 100 deg C in order to be classified as a 30wt oil, or a 40wt oil, and so forth. The above chart on oil viscosities shows the viscosity spread for each oil grade, and the following chart lists the specific limits for each grade of oil, as determined by the Society of Automotive Engineers (SAE), known as J300 specs for oil weight:
SAEJ300.jpg
Looking at the charts, we see that a 30 weight oil must have a hot viscosity between 9.30 and 12.49 cSt @100 deg C. Some 30wt oils may be a “thin” 30wt with a hot viscosity closer to 9.3 cSt, while some 30wt oils may be a “thick” 30wt with a hot viscosity closer to 12.49 cSt, but any oil with a viscosity in that range will be a 30wt oil. As an example, one 5W-30 oil has a viscosity of 9.7 cSt @ 100 deg C, while another brand's 5W-30 has a viscosity of 12 cSt @ 100 deg C. Both oils are 30wt oils, but one is physically thicker (more viscous) than the other. This also means that a 0W oil like 0W-30 can be a thicker oil than a 5W or 10W-30 when hot, despite being a thinner oil when cold.
What does the HTHS score mean for oils?
If you look at the data for your oil on the manufacturer’s website, you will probably notice an HTHS score along with the viscosity. The HTHS score is the oil’s viscosity at 150 deg C and refers to the oil’s ability to withstand “High Temperature & High Shear” conditions. Remember that thicker oils have higher film strength, and therefore withstand higher pressures and temperatures better than thin oils. Since HTHS is a function of viscosity, higher weight oils have higher HTHS numbers, and are better suited for extreme uses such as FI or racing.
What does the Viscosity Index of an oil mean?
Manufacturer’s usually list this value along with their viscosity measures. We have already seen that the working viscosity of an oil is measured at 100 deg C. An oil’s viscosity is commonly measured at 40 deg C as well. This is not the temperature the winter (“W”) weight of a multi-grade oil is measured at, it is simply considered the lower end of the oil’s operating temperature. Since an oil thickens as it cools, it’s important to make sure the oil doesn’t become any thicker than it’s weight allows at the cooler operating temperature. It’s also important to make sure that an oil operating at a lower temperature does not thin out to a lesser weight when it heats up. The ability of the oil to stay in it’s grade across a broad range of operating temperatures is known as the oil’s viscosity index. A higher viscosity index number means the oil better maintains it’s weight and tends to be more stable across a broad range of temperatures.
What are viscosity index improvers or modifiers?
These are chemical additives (polymers) that increase an oil’s viscosity with heat, to counter-act an oil’s tendency to thin with heat. They are primarily responsible for the ability of some oils to achieve a multi-grade oil weight, and to maintain a high viscosity index. However, an oil cannot simply “load up” on viscosity index improvers (VII’s) to create an oil with a high viscosity index, because VII’s are usually the first component to break down with heat and form sludge. When this happens, the oil will not stay in grade. There is a balance to the amount of VII’s that manufacturers can use and still keep their oil shear stable. Some oils can achieve a good vicosity index without using very many VII’s because they use high-end base stocks that are naturally very stable across a wide range of operating temperatures. The best way to determine if an oil is shear-prone from using too many VII’s to achieve the given grade is to have a UOA done.
What does a NOACK score mean?
Some manufacturers also report the NOACK scores as well. NOACK is an abbreviation for a test that determines an oil’s susceptibility to burn-off, or volatility. Oils with low NOACK scores lose less of their properties to volatility, keep their original protective qualities longer, and keep oil consumption lower than oils with higher NOACK scores. It can also indicate the base stocks in the formulation because an oil with high-end base stocks will use less VII’s, and since VII’s are the first to break down and oxidize, an oil that can use less VII’s will have a lower NOACK score.
Does the used oil’s color signal that it’s breaking down with use(oxidizing)?
If your oil is dirty looking, then that’s probably a good thing, since it means that the detergents in your oil are doing their job. A detergent is an oil additive that does several things to make your oil look dirty, but help your engine stay protected. First, they help neutralize the acids which adhere to the inside of the engine and cause sludge and varnish build-up. Detergents also suspend the soot and dirt that contaminates the oil with use. Finally, detergents help remove any sludge or varnish that has already formed inside your engine. Your oil’s color is not an indicator of how much it has sheared down and succumbed to soot or acids. Only a TBN (total base number) test will let you know if the oil’s ability to fight acid build-up and contamination is compromised.
What is a TBN test and how do I find the TBN of my oil?
The Total Base Number (TBN) is a relative number that describes how much base there is in your oil relative to the amount of acids that have built up. Oils that have high TBN numbers are going to maintain performance longer in the face of oxidation and soot build-up, and therefore are better for long drain intervals. Since an oil that uses fewer VII’s has a greater ability to resist sludge and acid build-up from oxidation, higher end synthetic base stock oils tend to have higher TBN values and maintain their performance longer than other oils. The TBN of new oil is often reported on an oil manufacturer’s data sheet for that particular oil. The TBN of used oil will be reported on a UOA if you elect to have a TBN test done. The UOA comparison charts have TBN values listed for those oils that had the test done. If you want to see if your oil is good for a longer drain interval, then contact one of the UOA labs and have a TBN test done on your sample.
How many miles should I drive before changing my oil?
If you want to stay in warranty, then follow Nissan’s guidelines. If you’re outside of warranty, or don’t care to follow Nissan’s guidelines while you’re in warranty, then there are oils which have been shown to protect the VQ engine for long drain intervals (over 12k miles). Check the comparison chart for oil samples with a high TBN value for a good option to use. However, if the car sees heavy track time or is FI, then normal oil change intervals may be in order- get a UOA to be sure.
Should I change my oil based on the time, or just the mileage?
As discussed, an oil’s performance degrades with use. Over time, the base stocks succumb to oxidation from heat, which leads to contaminate byproducts, varnish, and corrosion wear. Moisture degrades the base stocks (hydrolysis) and draws additives from suspension (water washing). Contaminates become catalysts for reactions, and can contribute to acid production (sludge). The viscosity Index improvers shear with use, and contribute to acid build-up and eventual base stock degradation. Even if you have low miles, but lots of time between oil changes, additives may fall out of suspension and moisture build-up will contaminate the oil. I personally don't usually go much longer than a year between oil changes, even with low mileage. A UOA will better inform you about when to change your oil by checking for additive depletion, a low TBN, and any moisture build-up.\
What is an oil’s base stock?
The base stock is the main component an oil is made of, before any additives are incorporated to achieve the final product. Which base stock is used determines how an oil is classified. The primary base stocks are divided into five classification groups for engine oils.
What are Group 1 and Group 2 base stocks, and which oils use them?
These are the non-synthetic base oil groups. These base stocks are made from conventional crude oils that have been refined to a point where it meets the standards set by the American Petroleum Institute for engine oil. Some conventional G2 oils perform as well as some synthetic oils in UOA's because of the excellent additive packages used to fortify the base stock. Such oils are cheaper than synthetic oils and offer excellent engine protection. However, G2 oils typically cannot achieve the same viscosity spread as synthetics, such as an 0W-40 oil weight. They also cannot protect as well as synthetic oils when it comes to severe heat and stress conditions like racing or FI. Also, because they use a base stock that is not as refined as the higher grouped oils, they do not typically have the stability needed for the extended oil change intervals that synthetic oils can achieve. It is important to look at the UOA results of G2 oils and see which have performed well. The better performing G2 oils are a good buy for the owner who does not need an extended oil change interval, or participate in heavy track use.
What is a Group 3 base stock, and what oils use it?
These oils are made from either a severely processed crude oil or slack wax feedstock. We’ll look at each separately:
1. Severely processed crude oils are known as “hydroisomerized” or “hydroprocessed” oils. These oils have gone through an advanced distillation process to remove undesirable crude hydrocarbons (like wax) from the crude oil base stock. Since the oil has been so thoroughly distilled through chemical processes, and only the “best” hydrocarbons remain in the oil, it is considered a synthetic. “Hydrocracked” oils, as they are also commonly called, are the most popular Group 3 base stock. These oils must have a VI over 120 and tend to have NOACK scores 11% or higher for a standard 30 weight oil.
2. Slack Wax Feedstocks are the only Group 3 oils not made directly from crude. The most popular oils that I know of that use slack wax as a base oil are from Shell. Sometimes referred to as XHVI oils, Shell manufacturers a base oil from synthetic slack wax which matches most PAO (group4) oil characteristics.
I’ve heard of Group 3+ oils, what are they?
G3+ oils are actually oils made from the new series of GTL base stocks. GTL (Gas To Liquid) allows an oil to meet the qualities of most PAO base stocks for less money. They are new, and able to achieve 0W-xx grades for engine oils due to VI and cold pour point measures that match PAO base stocks. They are made from a form of hydrocarbon synthesis known as the Fischer Tropsch process. This process is how the first synthetic oils were created, and is used with an isomerization sequence to make a very stable and effective base stock. These should become more popular in the future.
What is a Group 4 base stock, what is a PAO, and what oils use it?
These are oils whose base stocks come from fully saturated hydrocarbons known as polyalphaolefins, or PAO’s. They are synthesized from ethylene gas, which is a byproduct of refined crude oil. PAO base stocks are prized for their flexibility in making oils with a large viscosity index that perform well over a long oil change interval and under high stress. PAO oils are more stable in the presence of water and moisture than Esters, have very low pour points, and excellent thermal stability. What makes a PAO good in these areas also makes it a poor solvent, so PAO’s must be blended with another base stock in order to dissolve the additives that are included in the oil. Many racing oils are some type of Group 4 oil, and typically also work very well for street driven cars that see track use or are running some type of forced induction. Group 4 30wt oils tend to have NOACK scores between 6% and 9%.
What is a Group 5 base stock, and what oils use it?
This group includes Esters, Alkylated Napthalene, cycloaliphatics, silicones, silahydrocarbons, polyalkylene glycols, perfluoroalkylpolyethers, polybutenes, and any other fluids that do not fit in Groups 1-4. Esters and Alkylated Napthalene are the two most common, and we’ll look at each separately:
1. Esters are an aromatic hydrocarbon group found in many fruits and vegetables. They are commonly used as flavoring agents in drinks, and for their smells in perfumes. Esters are defined by the presence of one carbon atom and two oxygen atoms attached to the end of a hydrocarbon molecule. Since we have already seen by now that not all hydrocarbons perform the same (hence the whole need for Group classification), it can be assumed that not all Esters function the same in terms of engine oil. There are some 600 known Esters, and manufacturers have found that some Esters can be synthesized from natural resources and be very stable in extreme heat and stress, such as in a racing engine. Most Esters help swell and condition seals, and may be used as an additive in other oils for this reason. Esters also have a polar affinity to most metals, and this allows film strength under zero pressure. Some esters, such as polyolesters, are not hydrolytically stable and are not compatible with elastomer type seals. Most Ester based oils will have NOACK scores around 6% for a 30wt oil.
2. Alkylated Napthalene is a less common base stock. It is a synthesized aromatic hydrocarbon. The Alkyl group is introduced to Napthalene and forms a stable polycyclic structure that can be used to stabilize oxidation in the oil. It is usually not used as a base stock by itself, but as a Group 5 additive to other base stocks. Alkylated napthalene resists heat and oxidation better than mineral oil, PAO, or diester, is hydrolytically stable unlike polyolester, has good additive solvency, and is more elastomer compatible than esters. However, most napthanics don't have very high VI's.
Group 5 oils are the highest number base stock, why don’t they have the best UOA results?
Some Ester based oils perform worse than, or no better than, some oils using mostly Group 2 or 3 base stocks. One possible culprit is an Ester’s tendency for hydrolysis. As an oil is slowly degraded over time by oxidation, the result is more acids in the oil. These acids can break down the Ester into an alcohol and a carboxyl acid. This process is known as Ester Hydrolysis. Hydrolysis is also created by an introduction of water or moisture to the oil. It is not an issue when the engine is running hard for most of its oil change interval, such as in a racing series. This is because there is enough energy in the form of heat to catalyze the reverse reaction, that is, to re-create an Ester from the alcohol and carboxyl acid. For an oil that isn’t changed very often, unlike a racing engine, hydrolysis may be a factor. This is only one theory as to why Ester base stocks sometimes don’t perform better than other oils as seen from UOA’s. Another thought is included in this response from a tribologist in regards to a question of why Redline doesn’t do that well in UOA’s compared to other oils of “lesser” base stock:
Quote:
I have posted a lot on RL - I do not consider it the “last word” anymore. Esters of course are also susceptible to hydrolysis, which is an issue with cars not driven often. I think a lot of ester “hype” gets into the rL picture, and that the verbage used 20 years ago may not apply today. Plus, RL’s formulations are “old”, and while tried and true with lots of Ca and ZDDP, they do not post, as you pointed out, the numbers that indicate spectacular performance. I mean, esters should greatly reduce start-up wear due to their polar affinity, lubricity, film strength, etc. Yet, they are not much better (if at all) in wear reduction numbers than Chevron/Havoline. I think there is much going on at the nanotribologic level that may be being missed, and that new formulations from companies with deeper R&D pockets than RL may be on to these wear elements. So the amines and other “new age” additives may be more than just an answer to the reduction in “old school” AW’s like ZDDP. I thought differently as late as last year, but have amended my thoughts and statements to conform to proof - the UOA’s of the latest “thin”, min-based GF-4’s, for example.
As I said, there may well be something going on at the molecular level (nanotribologic) at the surface level of the metal - I just have not seen the science, and esters in engines are so tiny in the big picture that no one is doing the research. Esters are used in jets because of the temps involved - but that is exploited in RL advertising hype, IMO. But RL looks so good “on paper” - why would it not “kill” all the others? Most racing oils use some amount of ester, but that can be to offset seal performance issues of other synoil bases as much as to offer a performance benefit.
The subject of an ester’s performance as the "best" base stock for use in a street driven engine can be controversial, since there is no concrete answer. The fact is, some oils just perform better than others in the same engine. Therefore, choose an oil by what gives good results, not by the base stocks advertised.
Is an ester base oil better for racing than daily driving?
My opinion is that high Ester oils are better as a race oil, than a street oil. The real advantage Ester synthetic oils have over other synthetics is shear stability in the face of extreme heat. That benefit is going to be realized best in racing, and since high ester base oils have to rely on the additive package to offset some of the negative aspects of the ester base oil, such as moisture stability and elastomer compatibility issues, the typical wear protection of a good PAO or G3 in start/stop, short trip, and cold start stress will lend itself best to a street engine. Therefore, I think the value of Ester base oils are best realized in turbo VQ engines that see heavy track use, since they are seeing higher temps, and therefore the most important value for them is an oil’s HTHS score and extreme heat stability. Esters tend to shine in these circumstances. I think for daily-driven 350Z’s, a high Ester oil is a waste of money and not doing any favors for the engine. Of course, as I have already mentioned, a UOA should be the judge over how well an oil performs in your engine for your conditions, not speculation on base stocks.
I’ve heard that some oils labeled as synthetic are not true synthetics. What is the official definition of “synthetic”?
First, synthetic oils are not 100% synthetic unless you are buying just the base oil, since synthetic oils still use additives, and sometimes, a carrier oil. PAO based synthetic oils are a good example of this. Since PAO's are saturated hydrocarbons, they make for very poor solvents, and are therefore lousy at suspending additives. So, a PAO based synthetic must use another oil, like a Group3 product or AN or ester, as a carrier to hold the additive pack in suspension. Despite this fact, many companies believed that only majority PAO or G5 based engine oils should be called "synthetic", while companies like Castrol (owned by British Petroleum) and Shell used severely hydrocracked base stocks (Group 3) way back in the seventies, and called them synthetics. The API made an official definition of what constituted a synthetic during SAE Technical Meeting on Engine Oils 1, and hydroprocessed lubes qualified. The definition is:
Quote:
“Oils produced by synthesis (chemical reaction) rather than by extraction or refinement.”
In 1992, controversy began when Castrol used Shell base stocks (Group3 XHVI) for their synthetic line. In 1999, competing oil companies complained to the National Ad Council of the Better Business Bureau that it was misleading for Castrol to label their G3 based oils as “synthetic”. However, based on the API definition, Castrol was not in any violation of fair advertising policy. Further, the definition of synthetic was left open by the Ad Council for each company to determine for their own product line. This means that a “synthetic” oil must meet the API definition of being a synthetic, but one company’s synthetic line may use a G3 base oil, while another company’s synthetic line of oils might be G4, G5, or a blend of the three- it’s up to the manufacturer to decide.
So what Group of oil is the best?
There is no single group that is the all-around best. Some perform under specific circumstances and in specific engines better than others. Check for oil samples that consistently perform well in the VQ, and then you will see a clearer picture of what works and what doesn’t. It can be helpful to know what the differences in each group are, so that when someone says, “That’s only a G3 oil”, or “I only use Group 5 oils”, you’ll know what they mean. You should also realize by now that one base stock does not guarantee a better oil. There is far more to it. The combination of proper viscosity, additives used, and the type of base stock are all different for each oil. In fact, many tribologists say the additive package of an oil contributes more to it’s performance than the base stock.
What additives are used in engine oils, and what do they do?
Engine oil additives are an important piece of the puzzle in understanding how one oil can do a better job protecting an engine than another oil. Most oils have about 10-20% of their formulation in additives. These additives are what make up an engine oil’s composition above the base stock used. A lot of tribologists attribute an engine oil’s additive package as more important in terms of performance than the base stock. Posted below is a list of the different additives and modifiers used in engine oils to achieve their respective traits. The list is taken straight from Molakule on BITOG with my own notes on what elements may show up in a UOA from each additive:
Antifoamants or foam inhibitors (Protective Additive): polymers such as silicone polymers and organic copolymers of the silaxane’s; these create a lens that reduces an air bubble’s surface tension. Some oils are high in silicon because of this additive.
Antioxidants or oxidation inhibitors (Protective Additive): ZDDP, ZTDC, Moly TDC, Antimony TDC, aromatic amines such as organic tolutriazoles, thiadiazoles, diphenylamines, olefin sulfides, carboxylic acids; decomposes peroxides and terminates free radical reactions. Increases temperature of base oil at which base oil may tend to oxidize. Oxidation of oil promotes sludge particles and increases viscosity. May show up as zinc, phosphorous, and moly on a UOA.
Anti-Wear and Extreme Pressure Additives (Surface Protective Additive):
ZDDP, ZTDC, Moly TDC, Antimony TDC, Organic Sulfur-Phosphorus-Nitrogen compounds, Borates and Borate Esters, Tricresyl Phosphates, amine phostphates, and other phosphate esters, Chlorine compounds, and lead diamylcarbamates, lead and barium naphthenates, sulfurized olefins; protective film interacts at various temperatures and pressures to provide either a plastic interface or to provide a compound which shears at the surface- protecting the metal. May show up as zinc, calcium, phosphorous, boron, and moly on a UOA.
Demulsifier (Performance Additive): hydroxyalkyl carboxylic esters, alkenlycarboxylic esters; keeps water separated from lubricant.
Detergents (Surface Protective Additive): metallo-organic compounds of sodium, calcium, magnesium, boron phenolates, phosphates and sulfonates such as alkylbenzene sulfonic acids, alkylphenol sulfides, alkylsalacyclic acids; Lift deposits from surfaces to keep them suspended. May show up as phosphorous, boron, calcium, and magnesium on a UOA.
Dispersants (Surface Protective Additive): Alkylsuccinimides, alkylsuccinic esters (alkenyl succinimides); chemical reaction with sludge and varnish precursors to keep them acid neutralized and to keep them soluble. Detergent-dispersants often are the same chemical or come in compounds to accomplish the combined function(s).
Emulsifiers (Protective Additive): Polyisobutylenesuccinimides, alkenylsuccinate ester/salts. polyester amides, alkyl aminoesters; promotes a stable emulsion or mixture of oil and water.
Friction Modifiers or Friction Reducers (Performance Additive): Organic fatty acids and amides, lard oil, high molecular weight organic phosphorus and phosphoric acid esters such as Tricresyl Phosphates, ZDDP, ZTDC, Moly TDC, Antimony TDC, family of diphenylamines and amides, and olefin sulfides. Reduces coefficient of friction formulated lubricant in the boundary lubrication regime. Some VII’s also provide friction reduction. May show up as phosphorous, boron, zinc, and moly on a UOA.
Metal Deactivator (Protective Additive): ZDDP, ZTDC, Moly TDC, Antimony TDC, family of diphenylamines and amides, and olefin sulfides, heterocyclic sulfur-nitrogen compounds; inhibits corrosive effects of oxygen with metals and decreases metal interaction with oxygen compounds to reduce oxidation of oil. May show up as phosphorous, zinc, and moly on a UOA.
Rust Inhibitor (Surface Protective Additive): Barium sulfonates, amine phosphates, phosphordithioates, sodium thizoles (for coolants),
Pour Point Depressant (Performance Additive): polymethacrylates (PMA’s); reducing wax crystal formation and increases solvency of oil at low temperatures. May be part of VII package.
Seal Swell (Performance Additive): nitriles, specific esters, organic phosphates and aromatic hydrocarbons. Increases volume of elastomeric seals. May show up as phosphorous on a UOA.
Surfactants or Surface Active Agents (Protective Additive): family of diphenylamines and amides; usually part of the antioxidant package. Also provides enhanced friction reduction and allows oils to “climb” or spread on and over surfaces. Decreases but does not destroy surface tension
Viscosity Index Improver or Viscosity Modifier (Performance Additive): Olefin copolymers (OCP’s), hydrogentated styrene-diene copolymers, styrene esters, polymetharylates (PMA’s), mixed alkyl methacrylate-vinyl-pyrrolidines, aminated ethylene propylene, mixed alkylmethacrylate ethylene/propylenes; reduces viscosity change with temperature. Increases viscosity of base oil as temperature rises when base oil tends to thin. Some VII’s may also act as dispersants by incorporating dispersant compounds.
Are there particular additives I should look for in an oil, or avoid?
Not really. Some people like to look for high amounts of Moly or Boron in an oil, but just like base stock alone doesn’t determine the ability of the oil to perform well in your engine, the use of certain additives won’t guarantee a great performing oil, either. It’s the overall chemistry and how well an oil’s components work together that determines how well an oil performs in your engine for your needs. Which oils have the right chemistry to work the best for you can only be determined with a UOA.
Is Moly bad for my engine, like the Amsoil sales pitch says?
No. Moly is one of many compounds used in engine and gear oils to reduce friction. Amsoil likes to quote that Molybdenum Disulfide is banned by Cummins for use in their engines because it’s a solid and will damage the engine, and since their oils don’t use Molybdenum Disulfide it’s better for your engine. While Amsoil does make a good product, their advertising is a bit misleading. First, all additives, not just Moly, are by definition a solid. Second, while Amsoil may not use Moly Disulfide, they have used other Molybdenum compounds in some of their oils. Ans while Cummins does in fact state:
Quote:
“There is firm evidence that certain friction modifiers, molybdenum dithiophosphate for example, can in certain formulations result in cam follower pin failure at relatively low mileage”....
Amsoil fails to mention how this statement from Cummins applies to the use of assembly lubes, and not engine oil. The fact is, there are a number of oils which use Moly as an additive, even in the form of Molybdenum Disulfide, which are API and manufacturer approved. Most compounds of Molybdenum, however; are some form of the compound Molybdenum Trialkyldithiocarbamate (MoTDC, as noted in the additive list under friction modifiers). MoTDC is used in almost every engine oil made (ironically this includes some Amsoil formulations) and just like Moly Disulfide is approved for use in Cummins engines, along with every other engine manufacturer, including Nissan.
Are bottles of engine oil addtives good for my engine?
Depends on whom you ask. I say usually not, but it depends on the product. Slick 50 and other products that use Teflon (PTFE) to reduce friction should be avoided. If you have any non-stick Teflon cooking pans, then you know you’re not supposed to use metal utensils with them, right? Well, your engine is mostly metal-on-metal contact, and that’s not the ideal environment for PTFE. Slick 50 and it’s cousins were sued some years ago for this issue, and DuPont (the company which first made and trademarked Teflon) came out and said that while it didn’t recommend PTFE in the engine, they had done no testing to show it was detrimental for use in an engine. So, Slick 50 and others have gone on selling it. I wouldn’t touch the stuff. Now, there are some products that are simply common additives used by oil blenders, like those in the additives list above, that are bottled in concentrated form. Valvoline SynPower Oil treatment is an example. It contains MoTDC, some Borate Esters, Antimony TDC, and a lot of other common extreme pressure and anti-wear additives. There have been some good results with people adding some of this (usually an ounce per quart of oil) to their favorite oil and improving their UOA wear results.
What sources do you have for all this information?
This post offers a general introduction to Used Oil Analysis and basic lubrication fundamentals, in order that the 350Z community be better prepared for making sense of all the hype and choices they have when it comes to engine oils. It is not meant to be conclusive or all-encompassing. There is much more to this study, and anyone wishing to expand their knowledge would benefit from exploring my sources:
SAE Technical Papers pertaining to Used Oil Analysis
SAE paper 2007-01-1990: compares UOA data from individual engines running in a fleet of Taxi cabs, where they are running two different oils in the same family of engines, then the engines are torn down for visual inspection in an effort to determine the effectiveness of oils high in ZDDP versus the Taxis that used oils low in ZDDP. The UOA data was collected from individual cars, just as what has been done here, and trends for one oil to perform better than another were seen. The individual numbers varied from each engine, but the delta (the change in wear metals from the low ZDDP oil to the high ZDDP oil) is what was considered. High ZDDP oil did have less engine wear in the UOA’s, and was confirmed when the engines were torn down for inspection.
SAE paper 932838: compares UOA data from two LS1 engines in an effort to establish synthetic versus mineral oil degradation based on oil change interval length. They looked for trends to see if a synthetic oil would reduce wear over conventional.
SAE paper 2001-01-1899: compares UOA data from Chrysler V6 engines to determine if newer grades of GF-3 oils (which saw a reduction in AW/FM additives) are capable of meeting the lubrication requirements for DOHC, high performance, fuel efficient engines. There was a pattern for one type of oil to do better than another.
SAE paper 2004-01-1963: UOA data collected in intervals from another fleet test, every vehicle having the same model of engine, and the UOA results are compared from the urban transport fleet’s reference model engine to determine the effectiveness of UOA data. This test was extensive, but the conclusions speak for themselves, “wear rate has been identified as a more valuable parameter for engine wear condition, as obtained by wear concentration measurements directly obtained from spectrometry.” The paper concludes that individual ppm UOA numbers and ferrography numbers are misleading, that the trends of engine wear from multiple UOA’s are what should be considered.
SAE paper 2005-01-3818: Another UOA comparison paper from a Taxi fleet service, where 0W-20 and 5W-20 oils are compared. Same thing, wear rate trends between the two are what is considered.
SAE paper 981448: this paper discusses UOA data being used for evaluating oil drain periods, similar to the GM test, only different oils weren’t compared. The UOA’s were found to be very useful in determining an engine’s wear rate with a particular oil and when that oil is best changed out.
Other SAE Technical Papers
SAE TECHNICAL PAPER SERIES 2007-01-4133. The Effect of Oil Drain Interval on Valvetrain Friction and Wear.
SAE TECHNICAL PAPER SERIES 2000-01-2030. Film-Forming Properties of Zinc-Based and Ashless Antiwear Additives.
SAE TECHNICAL PAPER SERIES 2006-01-3439. API CJ-4: Diesel Oil Category for Both Legacy Engines and Low Emission Engines Using Disel Particulate Filters.
SAE TECHNICAL PAPER SERIES 770635. Anti-Wear Properties of Engine Oils - Effect of Oil Additives on Valve Train Wear.
SAE TECHNICAL PAPER SERIES 922301. Formulation Technology for Low Phosphorus Gasoline Engine Oils.
SAE TECHNICAL PAPER SERIES 2006-01-3413. Effect of Lubricant Properties and Lubricant Degradation on Piston Ring and Cylinder Bore Wear in a Spark-Ignition Engine
SAE TECHNICAL PAPER SERIES 932782. Influence of Engine Oil Viscosity on Piston Ring and Cam Face Wear.
SAE TECHNICAL PAPER SERIES 2000-01-1913. Impact of Fuel and Oil Quality on Deposits, Wear and Emissions from a Light Duty Diesel Engine with High EGR
SAE TECHNICAL PAPER SERIES 2007-01-1966. API CJ-4: Diesel Oil Category for Pre-2007 Engines and New Low Emission Engines Using Cooled Exhaust Gas Recirculation and Diesel Particulate Filters.
SAE TECHNICAL PAPER SERIES 2006-32-0013. Development of Long-Life Oil for Gas Engines
SAE TECHNICAL PAPER SERIES 810330. Engine Oil and Bearing Wear
Links
physicsworld.com
http://www.roymech.co.uk/Useful_Tabl...ubrication.htm
http://home.physics.wisc.edu/gilbert...ations/101.PDF
Oil Analysis and Lubrication Dictionary
http://www.engineersedge.com/lubrica...dge_menu.shtml
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