Here's that article I promised... THE GREAT OIL DEBATE: EXXON-MOBIL The designer of Mobil I V Twin 20W 50 joins in BY CHUCK GOLDMANN ABOUT CHUCK GOLDMANN... Chuck has worked for Exxon Mobil for almost 30 years. Since joining the company immediately afterreceiving his master's degree in chemical engineering, he has spent his entire career in research, workingon the development and testing of automotive engine oils, both Mobil I and conventional mineral oilproducts. Most recently, Chuck led the Mobil 1 Motorcycle Oil development effort. Chuck is also aHarley-Davidson owner and rider. His current_ bike is a 1999 Low Rider with big bore kit, flat-top pis tons,Mikuni carburetor, SE 203 cam, SE performance valve springs and SE air cleaner kit, all feeding into aHooker 2-into-I exhaust system. Chuck runs Mobil I V Twin 20W-50 in his engine, Mobil 1 75W90Synthetic Gear Lubricant in the transmission, and Mobil I MX4T I OW-40 in the primary. He changes allof these at the factory recommended 5,000-mile interval. Donny, as a big fan of your Techline articles, I’m sorry to say I can't completely agree with youradvice. I don't believe that automotive oils are just fine for your Harley. On the other hand, I doagree that synthetics are better than mineral oils, as long as we can agree on what we mean bysynthetic. AUTO OILS FOR MOTORCYCLES??? Simply put, automotive engine oils are not designed with motorcycle engine and/or transmissionrequirements in mind. With that said, one should always attempt to use a motorcycle engine oilas a first choice. Now, that's not to say that automotive engine oil would not work in a Harleyengine. However, our recommendation here is similar to what The Motor Company recommends(outside of HD 360 oil) in that any motor oil run in a Harley engine should meet the performancerequirements of an API C category (e.g. API CF, CF-4, CG-4, CH-4, etc.) oil. Oils that provideAPI C-type quality are formulated with the proper chemistry to provide some level of hightemperature diesel engine protection, depending on the category. As long as API C performanceis met, then an oil also rated as an API SH or SG quality product should function properly in anair-cooled H-D engine. So, on this point, The Motor Company and I are in agreement from thestandpoint that using automotive oils that do not meet the performance requirements of an API Ccategory in your bike is probably not a good idea. However, Harley continues in this area by stating that there are virtually no dual-qualifiedautomotive motor oils on the market (i.e. passenger car products which also offer API dieselperformance). The reason for this is that the higher level of deposit control additives required forAPI C performance often works to the detriment of fuel economy, and fuel economy is theprimary focus behind API SH and SJ. These points are true; however, Mobil 1 motorcycle oils,as well as all of the Mobil I automotive engine oils, meet the requirements of API SG, SH andCF So, there are at least a few oils currently on the market that offer both API S and Cperformance. Bottom line: I personally use Mobil I V Twin 20W-50 in my bike. If I were on the road anddown a quart, and I could not find Mobil I V Twin 20W-50, then I'd use Mobil I Tri-SyntheticFormula 15W-50. If I couldn't find that I'd use HD 360 20W-50. For me, any other automotiveoil would only be an avenue of last resort. MOTOR OIL FORMULATIONS – ADDITIVES When discussing additives that are used in engine oil formulations, the entire system must betaken into account, not just the individual components. After all, an engine oil formulation is likean engine: if you don't have all of the right components in the right sizes/quantities and allworking together in harmony, your engine won't run. Why is that? Well, there are several reasons. First, almost all additives are multifunctional, whichmeans they do more than one thing. Sometimes this multifunctionality is beneficial; sometimesit's not. For example, zinc and phosphorus containing anti-wear additives are also excellentantioxidants. Some of the most effective ashless dispersants, which keep sludge and dirt particlessuspended in the oil, attack certain seal materials causing them to harden and potentially leak.Friction modifiers like molybdenum, which help improve fuel economy in energy-conservingoils, promote high temperature deposit formation and must be compensated for with otheradditives. Also, just like base oils, additives are subject to oxidation and thermal degradation.They can break down and actually contribute to deposit formation. Additionally, additives cancompete with each other. If a friction modifier, for example, is too active it can keep the antiwear additive from reaching the metal surfaces, leading to excessive wear. As you can see, theadditive system used in any engine oil is more than just the sum of its parts. It is a complicatedsystem that has been carefully formulated to provide maximum performance, usually at aspecific cost. To make matters more complicated, when additives are mixed together before or asthey are added to a base fluid, they can react with each other and form new compounds that mayhave properties different from the original additives. Therefore, the order and temperature atwhich additives are mixed together is also important and must be controlled during manufacture. Okay, now let's look at the other half of the puzzle, base stocks. MOTOR OIL FORMULATIONS – BASESTOCKS The American Petroleum Institute (API) has divided all base stocks into five major groups. Ingeneral terms, as the group number increases so does the performance of the base stock and thecost of manufacture. However, one must keep in mind that, at the end of the day, it's the overallformulation (i.e. additives included) that dictates the performance of engine oil. Group I base stocks are your standard solvent refined mineral oils that have been around foryears. They contain sulfur and aromatics - some sulfur compounds have natural anti-wear andantioxidant properties while others can produce deposits, which is good and bad. Aromaticsprovide good solvency, which aids in additive solubilization and provides some naturaldispersancy. This is also good. However, aromatics are also easily oxidized, leading to oilthickening, which is bad. Group I base stocks have a wide molecular weight distribution. Thismeans they contain molecules that are both smaller and larger than you want for bestperformance. The smaller moleculesboil off at lower temperatures, and thelevel to which this occurs is referred toas the oil's volatility. Oil consumptionin an engine is related to an oil'svolatility level in that lower volatilitytypically means lower oil consumption(this is provided the engine itself is ingood mechanical condition). Thelarger molecules are more prone tothermal and oxidative degradation,leading to greater high temperaturedeposit formation. Group II and Group III base stocks are more refined via hydrofinishing or hydrocracking. Thislowers or removes sulfur and aromatics. While this helps minimize the bad features of Group Ibase stocks, mixed some of the positive features are also must be removed and must becompensated for with additives. Also, the molecular half weight distribution is narrowed, whichhelps to improve volatility. Most conventional mineral oils marketed in the U.S. use Group I base stocks. Group II basestocks will probably see (API) increased use with the introduction of o five the new API SL andILSAC GF-3 specifications likely to be issued next year. Group II stocks may be required tomeet significantly lower volatility requirements for low viscosity energy conserving oils. GroupIII base stocks are more prevalent in the European market where they are used primarily in midgradeand semi-synthetic products. In general, whether Group I, II, or III stocks are used, it's thecombination of the additive system with the base fluid system that will determine how well amotor oil formulation will perform. This brings us to Group IV and V base stocks. These types of base stocks are synthesized frombasic chemical building blocks. The advantage with this approach is that you end up with a basestock molecule that is specifically tailored for motor oil. In most parts of the world, Group IVand V base stocks are accepted as being synthetic, while Group I through III are referred to asmineral oils. The problem is that there is no industry-accepted definition of the term syntheticand, more importantly, in the U.S. there is no legally accepted definition for what the termsynthetic means. So when I refer to synthetic, I mean either a Group IV or V base stock.However, other marketers in the U.S. may consider products based on Group III and evenGroup II stocks as synthetic. Mobil 1 synthetic lubricants are based on one of three types of Group IV and V base stocks:polyalphaolefins (PAO) esters, or alkylated napthalenes. PAO’s are the basis of Mobil Isynthetic engine oils. They are made by taking ethylene - a clear, colorless gas consisting oftwo carbon and four hydrogen atoms - and reacting these molecules to form a 10-carbonatom chain, called decene (for 10). Decene becomes the basic building block for all the PAOmolecules. By hooking more and more of the decene chains together, you can tailor theviscosity grade from very thin to very thick. However, even though PAO molecules have exceptional thermal and oxidativestability, they have poor solvencyand seal swell characteristicsbecause they lack polar groups(groups that contain oxygen ornitrogen). Esters, on the other hand,are polar because they containoxygen and are made by combiningan acid and alcohol. This will leadto a reaction that gives you ester andwater. Esters also have exceptionalthermal and oxidative stability, andthey are excellent solvents andprovide good seal swell. Alkylafed naphthalene (AN) is aspecial kind of aromatic that is midwaybetween PAO and esters interms of solvency and seal swell, butprovides improved wear protectionover esters. By combining thesedifferent base stocks, it is possibleto create a base fluid system that hassuperior thermal and oxidativestability, yet maintains the samesolvency and seal swellcharacteristics of the tried and trueGroup I base stocks we have usedfor years. Mobil 1 motorcycle oilsuse a PAO/ester base fluid system,while Mobil 1 TriSyntheticautomotive oils also utilize alkylated naphthalene. In a nutshell, formulating and manufacturing engine oils is a complicated process thatinvolves a lot of engineering and a little bit of creativity. For this reason, the consumershould not get too wrapped up in formulation components and chemical analyses whenchoosing motor oil. Rather, base your decision on the reputation of the product and thecompany producing it as well as the performance and results that you experience personally.If this performance is aligned with cost and, more importantly, your expectations from thatbrand of motor oil, then you will be a happy rider. SYNTHETICS VS. MINERAL It's time to talk performance! Now, you can view the following as merely the biased opinionof an Exxon-Mobil employee who was also the chief engineer responsible for thedevelopment of Mobil 1 Motorcycle Oils. Or you can view it as the expert opinion ofsomeone who has spent the last 30 years developing and testing engine oils, is a Harley-Davidson owner and a H-D supporter. The Motor Company makes the point that your engine oil is the trash dump for the engine,which is correct. H-D states that all of the water, soot, and acids that are byproducts of fuelcombustion end up in the motor oil. (Actually, only some of these byproducts end up in themotor oil. The remainder go out with the exhaust gases.) H-D continues by stating that this isthe major source of particles that can form deposits in the engine. The Motor Company addsthat this is the reason for draining your oil and changing the oil filter at the intervalsrecommended. I agree completely. However, what The Motor Company overlooks is the factthat higher quality motor oils like Mobil I V Twin 20W-50, through carefully formulatedsynthetic technology and the use of high performance additives, can withstand the trash, evenat extended drain intervals. Further, The Motor Company's position on synthetics is that all motor oil breaks down in useand can be a source of engine deposits. Of course, H-D grudgingly admits that synthetics areinherently more resistant to oxidative and thermal breakdown. The Motor Company states,however, that this breakdown will only occur under severe conditions of lengthy exposure toextreme heat and that these conditions are not normally experienced in your typical car ormotorcycle. But what happens when you do encounter severe conditions and experience highoil temperatures...? OXIDATION One of the biggest differences between a Harley-Davidson and a passenger car is heat. Withan air-cooled engine, particularly in the case of the Twin Cams, where oil is sprayed directlyon the underside of the pistons for cooling, the engine oil can be subjected to very highlocalized and bulk temperatures. Since your Harley is air-cooled it tends to heat up when youare not moving, like sitting on Main Street in Daytona or Sturgis. If you've been there andbeen caught in traffic for an hour or so, you know what I mean. Your engine gets hot, youroil gets hot, and so do you. In these situations oil coolers don't help because they also onlywork when you have airflow. Ideally you want the bulk oil temperature in your bike to runbetween 215 and 225 degrees Fahrenheit, which is hot enough to boil off any fuel or waterthat has found its way into the oil system. Temperatures up to 240 degrees Fahrenheit are notuncommon and, under very severe conditions, you can see temperatures in the 280 to 300degree range. Okay, so what does that mean in terms of your oil? First, you have to understand how oilsoxidize. When oxidation occurs, the result is an increase in the viscosity of the oil untileventually, in the extreme, it becomes a black, sticky, semi-solid that will not provide anylubrication and ultimately will allow catastrophic engine failure. The general rule of thumbin the industry is that above 250 degrees Fahrenheit, the rate of oxidation doubles for every10 degrees increase in bulk oil temperature. This doesn't mean the oil viscosity increases in alinear fashion. Rather, it means that the time it takes for all of the antioxidant and the naturaloxidation resistance of the base stock to be used up is cut in half each time the temperatureincreases 10 degrees. Again, what does all this mean? One of the best ways to understand this is to look at oilthickening in an actual engine test. An easy way to do this is to run the oil in the same typeof engine and under the same test conditions used to measure oil oxidation performance inpast and present automotive industry tests. In this case, the test used involved a 3.8-liter V-6engine running at 3000 rpm, near wide-open throttle condition with the bulk oil temperaturemaintained at 300 degrees Fahrenheit. As shown in the accompanying graph, HD 360 20W-50 starts to break (dramatically increase in viscosity) after about 72 hours of operation and isessentially solid at 112 hours. In the same engine test, Mobil I V-Twin 20W-50 has notbroken after 256 hours of operation at which point the test was stopped. I like to call thisdifference performance reserve. For me, performance reserve provides peace of mind when Iencounter unusually severe operatingconditions. All of this leads to The MotorCompany's statement: “The questionthat the rider has to answer is‘Does the incremental benefit in theresistance to thermal breakdownafforded by the use of syntheticsversus fossil oils, in the absence ofextending oil drain intervals, make upfor the added expense of a syntheticfluid?’” Again the Motor Company and I arein complete agreement. This is thecrux of the issue. The MotorCompany states that “most (riders)will conclude using the right oil (HD360) for (their) engine and changing it and the filter at the recommended interval, is the bestand most cost efficient way to maintain (their) engine.” Now, if you only ride your bike under average conditions, and you desire to maintain yourengine at the lowest possible cost, then I agree with the Motor Company: use HD 360 andchange your oil and filter at recommended intervals. But if you're like me and you love your bike (just ask my wife), then you don't wantminimum cost performance or an average quality oil for the motorcycle on which you'vespent so much money and time. Or perhaps you have a modified engine and you like to ride\ nhard, or maybe you just don't want to have to worry about your oil holding up when you arestuck in city traffic. If any of these descriptions apply to you, then you are like me andhundreds of other Harley owners I've met. You want performance reserve to protect yourinvestment, and you want the peace of mind that goes along with that. You get both of thesewith Mobil I V Twin 20W-50. SYNTHETICS Where do the stories about synthetics come from and how dowe stop them? One on the most frustrating questions I'masked again and again is. "Don't synthetics wear flat spots onroller bearings because they are too slippery?" Okay, let's tryto end this once and for all. The short answer is no! See, allof the compounds we call synthetics are found in normalmineral oils. It's just that they coexist with a lot of othercompounds we don't want. You can either start with simplechemical building blocks and make only the compounds youwant and call them synthetic, or you could take regular crudeoil and refine and modify it until you come up with mostlythe same kind of stuff. It's just that no commercially viabletechnique to do the latter exists, so it's cheaper, although stillvery expensive, to go the synthetic route. The tractive coefficient, which is the measure of the easewith which a lubricant facilitates sliding, is essentially thesame for both mineral oils and synthetics. In other words,synthetics are not more slippery than mineral oils. Let's sayyou still don't believe me. Look at it another way. Supposesynthetics were vastly more slippery than mineral oil. Theonly way a roller bearing would not turn would be if you hadperfect hydrodynamic lubrication, which simply means thecam surface and the roller would always be separated by anoil film. In this case you would have perfect lubrication, themetal surfaces would never touch, you would have no wear,and it wouldn't matter if the roller turned or not. This neverhappens, which is why ZDDP is so important in your oil. By the way, Mobil I Tri-Synthetic automotive oils arefactory fill in all Corvettes. Vipers, and Porches, all of whichhave engines that use sophisticated roller/followertechnology, and they don't seem to have any problems withroller bearings not turning. The only way the roller will stopturning is if the needle bearings supporting the roller fail.Please, spread the word. At Daytona and Sturgis next year,I'd like to be able to not have to answer this question.
Additionally, additives cancompete with each other. If a friction modifier, for example, is too active it can keep the antiwear additive from reaching the metal surfaces, leading to excessive wear. As you can see, theadditive system used in any engine oil is more than just the sum of its parts.