AGGRAND Natural Lawn and Garden Products

Motorcycles have long been used as a popular means of general transportation as well as for recreational use. There are

nearly five million registered motorcycles in the United States, with annual sales in excess of three-quarters of a million

units. This trend is unlikely to change. As with any vehicle equipped with an internal combustion engine, proper lubrication

is essential to insure performance and longevity. It is important to point out that not all internal combustion engines are similarly

designed or exposed to the same types of operation. These variations in design and operation place different demands

on engine oils. Specifically, the demands placed on motorcycle engine oils are more severe than those placed on automotive

engine oils. Therefore, the performance requirements of motorcycle oils are more demanding as well.

Though the degree may be debatable, few will disagree that a difference exists between automotive and motorcycle applications.

In which area these differences are and to what degree they alter lubrication requirements are not clear to most

motorcycle operators. By comparing some basic equipment information, one can better understand the differences that

exist.

The following comparison information offers a general synopsis of both automotive and motorcycle applications.

There are six primary differences between motorcycle and automotive engine applications:

1. Operational Speed - Motorcycles tend to operate at engine speeds significantly higher than automobiles. This

places additional stress on engine components, increasing the need for wear protection. It also subjects lubricating

oils to higher loading and shear forces. Elevated operating RPMs also promote foaming, which can reduce an oil’s

load-carrying ability and accelerate oxidation.

2. Compression Ratios - Motorcycles tend to operate with higher engine compression ratios than automobiles.

Higher compression ratios place additional stress on engine components and increase engine operating temperatures.

Higher demands are placed on the oil to reduce wear. Elevated operating temperatures also promote thermal

degradation of the oil, reducing its life expectancy and increasing the formation of internal engine deposits.

3. Horsepower/ Displacement Density - Motorcycle engines produce nearly twice the horsepower per cubic inch

of displacement of automobile engines. This exposes the lubricating oil to higher temperatures and stress.

4. Variable Engine Cooling - In general, automotive applications use a sophisticated water-cooling system to control

engine operating temperature. Similar systems can be found in motorcycle applications, but other designs also

exist. Many motorcycles are air-cooled or use a combination air/oil design. Though effective, they result in greater fluctuations

in operating temperatures, particularly when motorcycles are operated in stop-and-go traffic. Elevated operating

temperature promotes oxidation and causes oils to thin, reducing their load carrying ability.

5. Multiple Lubrication Functionality - In automotive applications, engine oils are required to lubricate only the

engine. Other automotive assemblies, such as transmissions, have separate fluid reservoirs that contain a lubricant

designed specifically for that component. The requirements of that fluid differ significantly from those of automotive

engine oil. Many motorcycles have a common sump supplying oil to both the engine and transmission. In such cases,

the oil is required to meet the needs of both the engine and the transmission gears. Many motorcycles also incorporate

a frictional clutch within the transmission that uses the same oil.

6. Inactivity - Motorcycles are typically used less frequently than automobiles. Whereas automobiles are used on a

daily basis, motorcycle use is usually periodic and in many cases seasonal. These extended periods of inactivity place

additional stress on motorcycle oils. In these circumstances, rust and acid corrosion protection are of critical concern.

It is apparent that motorcycle applications place a different set of requirements on lubricating oils. Motorcycle oils, therefore,

must be formulated to address this unique set of high stress conditions.

The purpose of this paper is to provide information regarding motorcycle applications, their lubrication needs and typical

lubricants available to the end user. It is intended to assist the end user in making an educated decision as to the lubricant

most suitable for his or her motorcycle application.

The testing used to evaluate the lubricants was done in accordance with American Society for Testing and Materials (ASTM)

procedures. Test methodology has been indicated for all data points, allowing for duplication and verification by any analytical

laboratory capable of conduction the ASTM tests. A notarized affidavit certifying compliance with ASTM methodology

and the accuracy of the test results is included in the appendix of this document.

This document reviews the physical properties and performance of a number of generally available motorcycle oils. Those

areas of review are:

1. An oil’s ability to meet the required viscosity grade of an application.

2. An oil’s ability to maintain a constant viscosity when exposed to changes in temperature.

3. An oil’s ability to retain its viscosity during use.

4. An oil’s ability to resist shearing forces and maintain its viscosity at elevated temperatures.

5. An oil’s zinc content.

6. An oil’s ability to minimize general wear.

7. An oil’s ability to minimize gear wear.

8. An oil’s ability to minimize deterioration when exposed to elevated temperatures.

9. An oil’s ability to resist volatilization when exposed to elevated temperatures.

10. An oil’s ability to maintain engine cleanliness and control acid corrosion.

11. An oil’s ability to resist foaming.

12. An oil’s ability to control rust corrosion.

Individual results have been listed for each category. The results were then combined to provide an overall picture of the

ability of each oil to address the many demands required of motorcycle oils.

Two groups of candidate oils were tested, SAE 40 grade oils and SAE 50 grade oils. The oils tested are recommended

specifically for motorcycle applications by their manufacturers.

A lubricant is required to perform a variety of tasks. Foremost is the minimization of wear. An oil’s first line of defense is its

viscosity (thickness). Lubricating oils are by nature non-compressible and when placed between two moving components

will keep the components from contacting each other.With no direct contact between surfaces, wear is eliminated. Though

non-compressible, there is a point at which the oil film separating the two components is insufficient and contact occurs.

The point at which this occurs is a function of an oil’s viscosity. Generally speaking, the more viscous or thicker an oil, the

greater the load it will carry. Common sense would suggest use of the most viscous (thickest) oil. However, high viscosity

also presents disadvantages. Thicker oils are more difficult to circulate, especially when an engine is cold, and wear protection

may be sacrificed, particularly at start-up. Thicker oils also require more energy to circulate, which negatively affects

engine performance and fuel economy. Furthermore, the higher internal resistance of thicker oils tends to increase the operating

temperature of the engine. There is no advantage to using an oil that has a greater viscosity than that recommended

by the equipment manufacturer. An oil too light, however, may not possess sufficient load carrying ability to meet the

requirements of the equipment.

From a consumer standpoint, fluid viscometrics can be confusing. To ease selection, the Society of Automotive Engineers

(SAE) has developed a grading system based on an oil’s viscosity at specific temperatures. Grading numbers have been

assigned to ranges of viscosity. The equipment manufacturer determines the most appropriate viscosity for an application

and indicates for the consumer which SAE grade is most suitable for a particular piece of equipment. Note that the SAE

grading system allows for the review of an oil’s viscosity at both low and high temperatures. As motorcycle applications

rarely contend with low temperature operation, that area of viscosity is not relevant to this discussion.

The following chart identifies the viscosities of the oils before use. The purpose of testing initial viscosity is to ensure that

the SAE grade indicated by the oil manufacturer is representative of the actual SAE grade of the oil, and that it is therefore

appropriate for applications requiring such a fluid. The results were obtained using American Society for Testing and

Materials (ASTM) test methodology D-445. The fluid test temperature was 100° C and results are reported in centistokes.

Using SAE J300 standards, the SAE viscosity grades and grade ranges for each oil were determined and are listed below.

The results show that all of the oils tested except Lucas High Performance Motorcycle 10W-40 have initial viscosities consistent

with their indicated SAE viscosity grades. Those oils consistent with their indicated SAE viscosity grades are appropriate

for use in applications recommending these grades/viscosities.

An oil’s viscosity can also be affected through normal use. Mechanical activity creates shearing forces that can cause an

oil to thin out, reducing its load carrying ability. Engines operating at high RPMs and those that share a common oil sump

with the transmission are particularly subject to high shear rates. Gear sets found in the transmissions are the leading cause

of shear-induced viscosity loss in motorcycle applications.

The ASTM D-6278 test methodology is used to determine oil shear stability. First an oil’s initial viscosity is determined. The

oil is then subjected to shearing forces at 30 cycle intervals. Viscosity measurements are taken at the end of 30, 90 and

120 cycles and compared to the oil’s initial viscosity. The oils that perform well are those that show little or no viscosity

change. Oils demonstrating a significant loss in viscosity would be subject to concern. The flatter the line on the charts

below, the greater the shear stability of the oil. Each SAE grade was split into two or more groups to make the charts easier

to reference.

The results point out significant differences between oils and their ability to retain their viscosity.Within the SAE 40 group,

41.6% of the oils dropped one viscosity grade to an SAE 30. Within the SAE 50 group, 43.8% dropped one grade to an

SAE 40. Most of the oils losing a viscosity grade did so quickly, within the initial 30 cycles of shearing. Testing revealed that

Lucas 10W-40 High Performance Motorcycle oil was the only oil to shear to an SAE 20.

It should be noted that both high and low viscosity index oils exhibited significant amounts of shear and viscosity loss. Two

of the oils with the highest viscosity index, Torco T-4SR in the SAE 40 group and Yamalube 4R in the SAE 50 group, had

the largest drops in viscosity of all the oils in their respective groups. Torco T-4SR sheared to an SAE 30 and Yamalube

sheared to an SAE 40. Valvoline 4-Stroke SAE 50 and Castrol V-Twin SAE 50 had a comparatively low viscosity index and

they too lost significant viscosity, shearing down to an SAE 40.

Shear stability and good high temperature viscosity are critical in motorcycle applications. How these two areas in combination

affect the oil is measured using ASTM test methodology D-5481. The test measures an oil’s viscosity at high temperature

under shearing forces. Shear stable oils that are able to maintain high viscosity at high temperatures perform well

in the High Temperature/High Shear Test. The test is revealing as it combines viscosity, shear stability and viscosity index.

It is important because bearings require the greatest level of protection during high temperature operation. Test results are

indicated in cetipoises (cP), which are units of viscosity. The higher the test result, the greater the level of protection offered

by the oil.

Though viscosity is the most critical variable in terms of wear protection, it does have limitations. Component loading can

exceed the load carrying ability of the oil. When that occurs, partial or full contact results between components and wear

will occur. Chemical additives are added to the oil as the last line of defense to control wear in these conditions. These additives

have an attraction to metal surfaces and create a sacrificial coating on engine parts. If contact occurs the additive coating

takes the abuse to minimize component wear. The most common additive used in internal combustion engine oils is

zinc dithiophosphate (ZDP). A simple way of reviewing ZDP levels within an oil is to measure the zinc content. It should be

noted that ZDP defines a group of zinc-containing compounds that vary in composition, quality and performance. Quantity

of zinc content alone does not indicate its performance. Therefore, it cannot be assumed that oils with higher concentrations

of zinc provide better wear protection. Additional testing must be reviewed to determine an oil’s actual ability to prevent

wear. The tables below show the levels of zinc present in each of the oils. Results were determined using an inductively

coupled plasma (ICP) machine and are reported in parts per million.

Zinc levels varied widely in both the SAE 40 and 50 groups, ranging from as low as 860 ppm to as high as 2,465ppm.

The ASTM D-4172 4-Ball Wear Test is a good measure of the existence and robustness of an oil’s additive chemistry. It is

used to determine an oil’s ability to minimize wear in case of metal-to-metal contact. The test consists of a steel ball that sits

atop three identical balls that have been placed in a triangular pattern and restrained from moving. All four balls are immersed

in the test oil, which is heated and maintained at a constant temperature. The upper ball is then rotated and forced onto the

lower three balls with a load measured in kilogram-force (kgf). After a one-hour period of constant load, speed and temperature,

the lower three balls are inspected at the point of contact. Any wear will appear as a single scar on each of the lower

balls. The diameter of the scar is measured on each of the lower balls and the results are reported as the average of the

three scars, expressed in millimeters. The lower the average scar diameter, the better the wear protection of the oil. In this

case, the load, speed and temperature used for the test were 40 kg, 1800 RPMs and 150° C respectively.

Interestingly, the SAE 40 oils with the highest and lowest levels of zinc, Maxima Maxum 4 at 2,464 ppm and Lucas High

Performance Motorcycle at 860 ppm, had similar mid-range results. Royal Purple, with an average level of zinc (1,474 ppm)

had the largest wear scar (nearly 55% larger than the next closest wear scar size). Zinc levels for those oils performing the

best, AMSOIL MCF, Mobil 1 MX4T, Motul 300V Sport and Torco T-4SR ranged from 1,061 to 1,762 ppm.

The SAE 50 group showed a similar trend. Golden Spectro 4, with the highest zinc level (2,162 ppm), performed less than

average in the 4-Ball Wear Test, while the Motul 300 V Competition, with one of the lowest zinc levels (1,048 ppm), tied with

AMSOIL MCV and Torco T-4SR with the best test results.

The results strongly suggest that simply having high levels of zinc is not sufficient to effectively minimize wear.

Wear protection is provided by both the oil’s viscosity and its chemical additives. The greatest need for both is in the motorcycle

transmission gear set. High sliding pressures, shock loading and the shearing forces applied by the gears demand a

great deal from a lubricant. Motorcycle applications present a unique situation because many motorcycle engines share a

common lubrication sump with the transmission. The same oil lubricates both assemblies, yet engines place different

demands on the oil than do transmissions. What may work well for one may not work well for the other. In an attempt to

meet both needs, a lubricant’s performance can be compromised in both areas.

To examine gear oil performance, the ASTM test methodology D-5182 (FZG) is used. In this test, two hardened steel spur

gears are partially immersed in the oil to be tested. The oil is maintained at a constant 90° C and a predetermined load is

placed on the pinion gear. The gears are then rotated at 1,450 RPM for 21,700 revolutions. Finally, the gears are inspected

for scuffing (adhesive wear). If the total width of wear on the pinion gear teeth exceeds 20 mm, the test is ended. If less

than 20 mm of wear is noted, additional load is placed on the pinion gear and the test is run for another 21,700 revolutions.

Each time additional load is added, the test oil advances to a higher stage. The highest stage is 13. Results indicate the

stage passed by each oil.Wear is reported for the stage at which the oil failed.

The test shows that 58.3% of the SAE 40 grade oils and 75% of the SAE 50 grade oils passed stage 13. Note that in the

SAE 40 group, Mobil 1 MX4T, Motul 300V Sport and Torco T-4SR tied with AMSOIL MCF for the best 4-ball result but scored

among the lowest in the FZG gear test. In the SAE 50 group, Motul 300V Competition and Torco T-4SR tied with AMSOIL

MCV for the best 4-ball result, yet scored among the lowest in the remaining 25%. FZG and 4-ball wear tests measure wear

protection differently. High scores in both tests indicate superior wear protection in a variety of applications and conditions.

Only AMSOIL MCF (SAE 40) and MCV (SAE 50) placed on top in both wear tests.

Heat can destroy lubricants. High temperatures accelerate oxidation, which shortens the oil life and promotes carbon

deposits. Oxidized lubricants can create and react with contaminants such as fuel and water to produce corrosive by-products.

Oxidation stability is critical in air-cooled and high performance motorcycles.

ASTM test methodology D-4742 is used to determine an oil’s ability to resist oxidation by exposing the oil to common conditions

found in gasoline fueled engines. These conditions include the presence of fuel; metal catalysts such as iron, lead

and copper; water; oxygen and heat. Typically, the initial rate of oxidation is slow and increases with time. At a certain point,

the rate of oxidation will increase significantly. The length of time it takes to reach that level of rapid oxidation is measured

in minutes.

The test shows that 50% of the SAE 40 group oils and only 37.5% of the SAE 50 group oils achieved the maximum obtainable

results of 500 minutes. The results of the remaining oils suggest a faster rate of degradation and shorter service life.

Superior oxidation stability is obtained through a combination of oil base stock and additive technology. In addition to being

an anti-wear agent, zinc dithiophosphate (ZDP) is also an oxidation inhibitor. Similar to the discussion on wear, one might

assume that oils with higher levels of zinc would provide improved oxidation stability. However, the results show that high

ZDP levels were not consistent with good oxidation stability in the TFOUT test.

When oil is heated, lighter fractions in the oil volatilize (evaporate). This leads to increased oil consumption, emissions and

viscosity increase. Higher operating temperatures produce greater volatility.

To determine an oil’s resistance to volatility, ASTM test methodology D-5800 is used. In this test, a specific volume of oil is

heated to a temperature of 250° C for a period of 60 minutes. Air is drawn through the container holding the oil sample,

removing oil that has turned into vapor. At the end of the 60-minute period, the remaining oil volume is weighed and compared

to the original weight of the sample. The difference is reported as the percentage of weight lost.

The results show a significant difference between those oils with low volatility and those with higher volatility. Low volatility

is of particular benefit in hot running, air-cooled engines.

Motor oils are designed to neutralize acids and keep engines clean. Both tasks can be accomplished, in part, through the

use of detergent additives, as they are often alkaline in nature. The extent to which alkalinity exists within an oil can be

measured using ASTM D-2896. Reported as a Total Base Number (TBN), the test determines the amount of acid required

to neutralize the oil’s alkaline properties. The higher the result, the greater amount of acid the oil can withstand.

Detergent additives are sacrificial and are depleted as they neutralize acids. Therefore, oils with a higher TBN should provide

benefits over a longer period of time.

During engine and transmission operation, air is introduced into the lubricating oil, which may produce foam. In severe

cases, foam can increase wear, operating temperatures and oxidation. Oil is non-compressible, but when air passes

through loaded areas, the bubbles can collapse and allow the metal surfaces to contact each other. In addition, the oil has

a larger surface area exposed to oxygen when air is trapped in the oil, which promotes increased oxidation.

Higher operating speeds and gear systems in motorcycles increase the need for good foam control. While oil cannot prevent

the introduction of air, it can control foaming through the use of anti-foam additives.

To determine foaming characteristics, ASTM test methodology D-892 is used. The testing is divided into three individual

sequences. In each sequence, air is bubbled through the oil for five minutes and the foam generated is measured in millimeters

immediately following the test. At the end of the sequence, the oil is allowed to settle for 10 minutes and the remaining

foam is measured again. Both results are reported. The temperature is altered for each sequence. Sequence I is conducted

at 24° C, Sequence II at 93.5° C and Sequence III after allowing the oil to cool back to 24° C.

The amount of foam after the 10 minute settling period for all oils in all sequences was zero. The results shown are the levels

of foam present for each sequence immediately following the five-minute bubbling process.

Rust protection is of particular importance in motorcycle applications. Motorcycles are typically not used every day and are

often stored during the off-season. Condensation and moisture within the engine can cause rust. Rust is very abrasive and

leaves pits in metal surfaces. Rust rapidly accelerates wear and can cause catastrophic failure. Roller bearings are especially

sensitive to rust. Oil, however, has little or no natural ability to prevent rust. General engine oil additives may provide

some degree of rust protection, but for superior anti-rust properties, rust inhibitors must be added.

Rust protection is measured using the ASTM D-1748 humidity cabinet test. The procedure calls for metal coupons to be

dipped in the test oil, then placed in a humidity cabinet for 24 hours at 48.9° C. After 24 hours, the coupons are removed

and inspected for rust. Oils allowing no rust or no more than three rust spots less than or equal to 1 mm in diameter are

determined to have passed. Oils allowing more than three rust spots or one rust spot greater than 1 mm in diameter are

determined to have failed. The degree of failure has been divided into three additional categories: 1-10 spots, 11-20 spots

and 21 or more spots.

Performance is not all that is considered when making a motorcycle oil purchase. The consumer will wish to optimize the

performance of the product as compared to the price. In this evaluation the price of the candidate oils were compared on

a cost per ounce basis, equalizing the differences between quart and liter volumes. Prices are based on the actual cost

paid for the product when purchased in case lots.

Although the initial price of a product is a primary concern, it does not reflect the actual cost of using the product. Less

expensive oils may save money initially but can cost more in the end if they compromise performance. The additional benefits

offered by a more expensive oil can offset the difference in price. For example, oils that last longer cost less over time,

and oils that offer superior anti-wear performance and rust protection can increase equipment life, reducing expensive

repairs. High quality motorcycle oil is an inexpensive way to protect an expensive investment.

It has been noted that motorcycle oils must be multi-functional, meeting the needs of both the engine and transmission. An

additional concern is in those applications in which the clutch is immersed in the oil occupying the transmission. As the

clutch is a frictional device and oils are by design used to minimize friction, concern arises over the impact the oil may have

on the operation of the clutch. How an oil performs in a wet-clutch application is, in part, a function of its additive system.

An oil should be free of additives such as friction modifiers that can dramatically alter the dynamic and static frictional properties of the clutch and result in clutch plate slippage.

Wet-clutch compatibility is determined using JASO T 904-98 test methodology. This procedure determines the frictional

characteristics of an oil and allows for comparison against a standard. That standard has two categories: JASO MA and

MB. For motorcycle applications, the best performance is generally obtained when oils meeting the JASO MA specifications

are used.

The scope of this paper did not allow for the evaluation of all oils in this area. As such, results of the oils tested were not

included in the overall product summary. The results provided are for interest only.

Each oil was assigned a score for each test result. The oil with the best test result was assigned a 1. The oil with the second

best result was assigned a 2, and so on. Oils demonstrating the same level of performance were assigned the same number.

Note that the results of each test have not been weighted to reflect or suggest the degree of significance it represents

in a motorcycle application. The degree of significance will vary between individual applications and by consumer perception.

As oils must perform a number of tasks, results in all categories were added together to produce an overall total for each oil.

The oil with the lowest total is the overall highest performer.

The intent of this document is to provide scientific data on the performance of motorcycle oils and information on their

intended applications. The document also attempts to dismiss several rumors or mistruths common to motorcycle oils. In

doing so, it will assist the reader in making an informed decision when selecting a motorcycle oil.

The tests conducted are intended to measure variables of lubrication critical to motorcycles, with some having much greater

value than others. Gear and general anti-wear protection, oxidation stability and rust protection are the most important, with

zinc content being among the least important. The results were not weighted based on importance. The value of each test

is to be determined by the reader.

The data presented serves as predictors of actual service; the better the score, the better the performance. AMSOIL MCF

and MCV demonstrated superior performance, particularly in the most important areas, and each ranked first overall in its

respective category. It should be noted that the performance of a given manufacturer’s oils was not always consistent

between viscosities. For example, Motul 300V Sport scored second within the SAE 40 group while Motul 300V Competition

scored ninth in the SAE 50 group.

The results suggest a relationship between the cost of an oil and its level of performance. Generally, higher priced oils tend

to perform better, although price alone is not a guarantee of performance. Motul 300V Competition was the most costly oil

tested, yet lower priced oils showed better performance. Price must be put into perspective. The cost of oil compared to the

cost of a motorcycle is minimal. The cost difference between the average price for motorcycle oils and the most expensive

oils is about $10 per oil change. If the performance of an oil can support an extended oil change interval, that cost is

reduced. The consumer must consider the performance and benefits offered by an oil and how those benefits affect their

motorcycle investment to determine the oil’s value.

In conclusion, maximum performance and cost effectiveness are obtained when one looks beyond marketing claims and

selects a product based on the data that supports it.

1. SAE Viscosity Grades for Engine Oils - SAE J300 Dec 99

2. JASO T 904-98

3. ASTM Test Methodology Designation: D 892-03

4. ASTM Test Methodology Designation: D 1748-00

5. ASTM Test Methodology Designation: D 2270-04

6. ASTM Test Methodology Designation: D 2896-03

7. ASTM Test Methodology Designation: D 4172-94 (Reapproved 2004)

8. ASTM Test Methodology Designation: D 4742-02a

9. ASTM Test Methodology Designation: D 5182-97 (Reapproved 2002)

10. ASTM Test Methodology Designation: D 5481-04

11. ASTM Test Methodology Designation: D 5800-00a

12. ASTM Test Methodology Designation: D 6278-02

MCF) SAE 10W-40 Synthetic Motorcycle Oil
(MCV) SAE 20W-50 Synthetic Motorcycle Oil