Base Oils & Lubricant Performance

By Anthony Garner

Introduction

The purpose of this thread is to open up productive conversation into the various kinds of base oils used in motor oil finished products. We will also look at how automotive lubricants are marketed as well as theory into lubricant heat control and friction reduction. This thread is not intended to be the final word, but rather an ongoing discussion where all are encouraged to contribute. Please provide links and or cited sources whenever possible.


Motor Oil Base Stocks

Base Stock: A motor oil base stock is usually refined from petroleum or a selected synthetic material. It is the main foundational component of the oil into which additives are blended to create a finished lubricant. Currently, the American Petroleum Institute (API) divides motor oil base stocks up into five separate group categories listed below.

Theory: Conventional Motor Oil

"Conventional lubricants are refined from crude oil. Refining is a process of physically separating light from heavy oil fractions. Crude oil is a natural substance. It contains millions of different kinds of molecules. Many are similar in weight but dissimilar in structure. Because refining separates products by weight, it groups molecules of similar weight and dissimilar structure, so refined lubricants contain a wide assortment of molecules.

However, not all of those molecules are beneficial to the lubrication process. Some of the molecules found in refined lubricants are detrimental to the lubricated system or to the lubricant itself. For example, paraffin, a common refined lubricant component, causes refined lubricants to thicken and flow poorly in cold temperatures. Some refined lubricant molecules also may contain sulfur, nitrogen, and oxygen, which act as contaminants and invite the formation of sludge and other by-products of lubricant breakdown." - Amsoil, Inc.

Theory: Synthetic Motor Oil

"Synthetic lubricants are not refined. They are chemically engineered from pure chemicals.

Pure – Because they are derived from pure chemicals. Synthetic lubricants contain no contaminants or molecules that “don’t pull their own weight.”

Uniform – Because synthetics contain only smooth lubricating molecules, they slip easily across one another. On the other hand, the potpourri of jagged, irregular and odd-shaped molecules of refined lubricants don’t slip quite so easily. The case with which lubricant molecules slip over one another affects the lube’s ability to reduce friction, which in turn, affects wear control, heat control and fuel efficiency.

Heat Control – Because uniformly smooth synthetic lubricant molecules slip easily over one another, they are superior friction-reducers to conventional lubricants. (Technically, because they slip more easily over one another, synthetics are said to have a lower “coefficient of friction” than conventional lubricants.) The less friction in a system, the less heat in it, too. Friction and heat are two major contributors to component failure and wear. By controlling friction and heat more effectively, synthetics significantly reduce the incidence of component failure and significantly reduce the rate of component wear." Amsoil, Inc.

The “Synthetic” Controversy

The topic of base oils and their perspective level of performance is generally a controversial topic among motor oil enthusiasts and on up through oil industry experts. Even defining what “synthetic” means results in controversy. Evidence of this can be seen by the conflicting comments made by oil industry experts after the much famed 1999 National Advertising Division (NAD) cases which defined the way synthetic lubricants would be labeled in the United States. In short, the result of the case ruled in favor of Castrol North America Inc. against the claim made by Mobil Oil Corp., that Castrol was not truthful in their advertising. The NAD ruling ultimately changed the way synthetic lubricants would be marketed in the United States setting the stage for what are known as group III lubricants to be labeled as synthetic. See the full two part article, A Defining Moment For Synthetics. Many would agree that the implication of the ruling blurs the lines of what a true synthetic lubricant really is and the levels of performance potential among the various base oil categories. In addition, some argue that this ultimately gives oil industry marketing the upper hand and leaves consumers at a disadvantage. A trip the local auto parts store reveals a dizzying array of synthetic motor oil choices. Terms like Full Synthetic, 100% Synthetic, Semi-Synthetic, Synthetic Blend and Synthetic Plus all grace the covers of motor oil bottles. Without further research, this often leaves one to wonder which version of synthetic motor oil best suites their specific application. Research into synthetic motor oils may also lead one to decide that top tier synthetic lubricants are not the best value for their dollar, while others may draw the conclusion that they will use nothing but top tier synthetics. The reality is that when considering such variables as driving habits, climate conditions, and equipment design, some motor oils fit some applications better than others, having their own proprietary blend of base oils and additives which make for a unique finished product.

For comparison, we will use three different motor oils as examples to help illustrate how motor oils are formulated using the various base stocks, how they are marketed, their associated cost, and discuss the perceived levels of performance each lubricant has.

Lubricant #1: Conventional Motor Oil

Chevron Supreme SAE 5W-30 API (SM)
Base stock – API Group II
Retail price per quart $2.99

Base Stock Origin: Refined from crude oil.

Today, conventional motor oils are formulated with Group II base stocks.

Other examples of Group II motor oils include but are not limited to Pennzoil (Yellow Bottle), Castrol GTX, Quaker State Peak Performance, Valvoline Conventional, Schaeffer Supreme 7000 Synthetic Plus, Brad Penn, and Shell Rotella T.

Note A: Advancements in oil technology like those pioneered by the Chevron Corporation have greatly improved the quality of conventional motor oils and have given way to group III synthetic motor oils. Read more on group II and III oil technologies at Chevron U.S.A Inc. and Shell Oil Company. Some have argued that this type of technology has closed the gap in performance between conventional motor oil and top tier synthetic lubricants.

Note B: Retail pricing provided by CSK Auto, Inc., and Amsoil, Inc., as of 10/18/09

Lubricant #2: Full Synthetic Motor Oil

Pennzoil Platinum SAE 5W-30
Base stock - API Group III
Retail price per quart $6.99

Base Stock Origin: Refined from crude oil.

Group III oils are refined from crude oil and are commonly marketed as “Full Synthetic” motor oil.

Other examples of Group III motor oils include Castrol Syntec, Amsoil Extended Life Synthetic Motor Oil, Schaeffer Supreme 9000 Full Synthetic, Shell Rotella T Synthetic, and Royal Purple High Performance Motor Oil.

Refer to notes A and B

Lubricant #3: 100% Synthetic Motor Oil

AMSOIL 100% Synthetic SAE 5W-30 Motor Oil
Base stock - API Group IV/V
Retail price per quart $8.75

Base Stock Origin: Pure chemicals derived from Crude Oil or Natural Gas.

Other examples of Group IV/V motor oils include Red Line, Royal Purple eXtreme Performance (XPR) Racing Oil, and Mobil 1.

Refer to note B.

100% Synthetic motor oils are often referred to as Top Tier Synthetics or Polyalpholefin (PAO) group IV based lubricants. Although PAO Group IV base stocks are not refined from crude oil like Group II and III oils are, there can still be some basis in crude oil. Ethylene is a colorless gas that is commonly derived from crude oil or natural gas. In addition to being a building block for Group IV synthetic base stocks, other products made from the ethylene family can also include plastics and rubber. Group V Ester oils are commonly used as additives in PAO based synthetic motor oils to improve various aspects of the finished product. See also Esters In Synthetic Lubricants. Finally, while many companies utilize PAOs in their finished products either as the main base stock or as an additive, there are only four companies currently in the United States that produce PAOs. According to the October 29, 2008 edition of Lube Report, producers of PAOs in the US include Chevron Phillips Chemical, ExxonMobil Chemical, Ineos Oligomers, and Chemtura. See also, Synthetic Lubricants.


Debate: Friction and Heat

Another area of debate among the oil industry experts is how the various base stocks perform with respect to coefficient of friction and heat reduction. For some, the conclusion has been made that with the advancements in base stock technology, there is little or no difference with respect to coefficient of friction and heat reduction between Group II/Group III and Group IV oils. However, this argument does not hold true for others. Some experts have indicated that PAO oils, or PAO oils blended with Ester oils both offer friction reducing abilities. Further, the purported added benefits of using a motor oil with friction reducing abilities include increased horsepower , higher rpm range, improved fuel economy, and lengthened engine component life. Provided below is responses from oil industry experts Tom Schaefer, formerly of the Hatco Corporation, and Ed Kellerman, manager of Oil Analyzers Inc., a subsidiary of Amsoil, Inc. Also provided is a related experience from an automotive Internet forum member.

Below, Ed Kellerman and Tom Schaefer comment about base oil characteristics with regards to Group IV Synthetic motor oils and friction reduction when compared to modern day Group II conventional motor oils.

"If we are talking just straight base stock, with no other additives, then group IV basestocks reduce friction far greater than groups II or III. You are correct: it’s a function of even molecular structure vs. molecules of all different shapes and sizes. The base stock argument, however, is for the most part irrelevant, in that there is so much more to a finished engine oil than just the base stock. It is possible to take a lesser base stock and improve anti-frictional characteristics by using high quality additives such as viscosity index improvers, anti-wear additives, friction modifiers, etc... Conversely, you can have a super high quality group IV base stock that if formulated with inferior additives and not formulated correctly, may not offer higher performance than a properly formulated group III finished engine oil. This is what makes the basestock argument irrelevant when it comes to the performance of a finished oil. AMSOIL engine oils are made from the finest base stocks and additives and there is no way any finished group II or III engine oil could come close." - Ed Kellerman

"A good group IV formulation will run cooler. This is not as important, however, as the fact that a group IV are far more resistant to thermal breakdown in high heat conditions, thereby offering far superior protection compared to groups II and III.

An oil's effect on engine temperature is a function of viscosity, coefficient of friction, and heat transfer properties. I don't doubt that these properties are similar among group I - IV hydrocarbons as they are all in the same chemical family, that is, there would be some differences based on such factors as aromatic content and molecular weight distribution, but the differences should be relatively small. Between different chemical families, however, the differences can be significant. Esters, for example, have significantly lower coefficients of friction and better heat transfer rates than most hydrocarbons, and much lower engine oil temperatures were frequently reported from the original all ester formulations back in the 1970s.

Since modern synthetic oils today are based almost entirely on hydrocarbon base oils, I wouldn't expect to see much difference in engine temperatures when viscosities are equal, especially since friction modifier additives are more potent than the base oils. That being said, those formulations with larger quantities of esters or ANs may indeed show some lowering of friction and temperatures." - Tom Schaefer

An automotive Internet forum member describes his experiences with lower engine operating temperatures when comparing conventional and synthetic motor oils.

"I work on an off-road race truck and we run oil temp gauges and found the following: During a fifteen minute race our oil temps would get up to 300+ if using any non synthetic oils. Mobil 1 dropped the oil temps by about twenty degrees to 280 and switching to Amsoil we dropped it to about 250-260 .......this is not representative of everyday usage but keep in mind that the water temp stays always in between 180-200 at all times no matter which oil.....so all in all it is kind of an accepted opinion that Mobil 1 is the cheapest and least effective of the synthetics but all of the higher end oils.......Amsoil, Royal Purple, etc. work better under extreme conditions. I guess it all depends on what your uses are. I just have my own opinions formed because of the info stated above." - LS1.com, Liquifire

Kellerman and Schaefer’s statements show slightly differing views with respect to the coefficient of friction of oil base stocks in their own right. However, both men seem to agree that a properly formulated lubricant with a quality additive package will provide improved anti-friction capabilities when compared to other lubricants using lower-grade additives. The exact rate to which friction reduction occurs between dissimilar finished lubricants is currently unknown. Further, a request was made for any relevant test data or studies on this subject, but none have been provided or located as of this writing. Mr. Kellerman did offer to review any information that would indicate no difference in friction reducing performance between GroupII/GroupIII and Group IV oils.

Further Discussion

While using cost effective Group II/III refined crude oil lubricants in mild-to-mid range performance applications can provide satisfactory results, other more demanding applications may gain additional benefits from utilizing Group IV based oils. Some example include, cooler engine operating temperatures, increased power and rpm ranges through friction reduction, lengthened oil change intervals, and better volatility and cold flow properties. Hopefully, after reading this post, one will come away with greater understanding and appreciation of what goes into producing a balanced lubricant, why some are cost effective, and why costly alternatives may offer a degree of increased performance potential.


For more information about AMSOIL synthetic lubricants and performance filtration products contact Anthony Garner at Competition Synthetics. Anthony is an Amsoil T-1 Certified Independent Dealer. E-mail Anthony at compsyn@live.com, or visit http://competitionsynthetics.com