FIELD
[0001] The present disclosure relates to lubricant compositions and methods utilizing the
lubricant compositions to provide and/or improve anti-shudder capabilities of automotive
transmission fluids. The present disclosure also provides lubricant compositions that
provide and/or improve compatibility with elastomeric components.
BACKGROUND
[0002] New and advanced transmission systems are being developed by the automotive industry.
These new systems often involve high energy requirements. Therefore, friction materials
technology must be developed to meet the increasing energy requirements of these advanced
fluid systems.
[0003] The high speeds generated during engagement and disengagement of some of the newer
transmission systems mean that a friction system must be able to maintain a relatively
constant friction throughout the engagement. It is important that the frictional engagement
be relatively constant over a wide range of speeds and temperatures in order to minimize
"shuddering" of materials during transmission power shift from one gear to another.
[0004] In particular, new high energy type friction materials are being developed and used.
The new high energy friction materials are able to withstand high speeds wherein internal
transmission plate surface speeds are up to about 65 m/second. It is also important
that the friction material be useful under limited lubrication conditions. One such
material being developed for automatic transmission applications is a carbon fiber
containing material.
[0005] In view of new materials and greater demands on transmissions, automotive power transmission
fluids are called upon to provide specific frictional properties under very demanding
conditions of speed, temperature, and pressure. Changes in a fluid's frictional properties
as a function of relative sliding speed, temperature, or pressure may cause performance
degradation immediately noticeable to the vehicle operator. Such effects may include
unacceptably long or short gear shifts, vehicle shudder or vibration, noise, and/or
harsh shifts ("gear change shock"). Thus, there is a need for transmission fluids
that exhibit improved characteristics such as shear and friction stability at high
temperatures and pressures. Such fluids would reduce equipment and performance problems
while improving the interval between fluid changes. By enabling smooth engagement
of torque converter and shifting clutches, these fluids may reduce shudder, vibration,
and/or noise, and in some cases improve fuel economy, over a longer fluid lifetime.
[0006] Friction modifiers are used in transmission fluids to control friction between surfaces
(e.g., the members of a torque converter clutch or a shifting clutch) at low sliding
speeds. The result is a friction vs. velocity (u-v) curve that has a positive slope,
which in turn leads to smooth clutch engagements and minimizes "stick-slip" behavior
(e.g., shudder, noise, and harsh shifts). Many conventional friction modifiers, however,
are thermally unstable. Upon prolonged exposure to heat, these additives decompose,
and the benefits they confer on clutch performance may be lost.
[0007] In addition, deterioration of structural elastomeric elements or components such
as seals, belts, gaskets, bushings, filters, and/or hoses in engines, transmissions,
gears, and/or axles may occur. Such deterioration may be attributed to interactions
between the elastomeric material of said elements and the reactive or deteriorative
components of a lubricant composition or fluid. Further, a lubricating fluid should
provide appropriate swelling of seals, gaskets, and the like. It is additionally an
object of the compositions and methods of the present invention to reduce the deterioration
of, improve the compatibility with, and promote proper swell of such seals, hoses,
and like elements and components.
SUMMARY OF EMBODIMENTS
[0008] In an embodiment, a power transmitting fluid for use in a power transmitting device
may comprising a major amount of a base oil and a minor amount of an additive composition.
The additive composition may comprise at least one non-dispersant viscosity index
improver, wherein the power transmitting fluid provides anti-shudder performance to
the power transmitting device.
[0009] In another embodiment, a lubricating fluid having compatibility with an elastomeric
component may comprise a major amount of a base oil and a minor amount of an additive
composition having at least one non-dispersant viscosity index improver.
[0010] In another embodiment, a method of improving the anti-shudder capabilities of a power
transmission fluid may comprise lubricating a power transmission with a power transmission
fluid comprising a major amount of a base oil and a minor amount of an additive composition
comprising at least one non-dispersant viscosity index improver.
[0011] In another embodiment, a method of improving the torque performance of a power transmission
fluid may comprise lubricating a power transmission with a power transmission fluid
comprising a major amount of a base oil and a minor amount of an additive composition
comprising at least one non-dispersant viscosity index improver.
[0012] In another embodiment, a method of improving the compatibility of a lubricating fluid
with an elastomeric component may comprise lubricating an elastomeric component with
a fluid comprising a major amount of a base oil and a minor amount of an additive
composition comprising at least one non-dispersant viscosity index improver.
[0013] In another embodiment, a method of promoting seal swell of an elastomeric seal may
comprise lubricating the elastomeric seal with a lubricating fluid comprising a major
amount of a base oil and a minor amount of an additive composition comprising at least
one non-dispersant viscosity index improver.
[0014] In another embodiment, a method of making a power transmitting fluid having anti-shudder
capabilities may comprise adding to a major amount of a base oil a minor amount of
an additive composition having a non-dispersant viscosity index improver.
[0015] In another embodiment, a method of making a lubricating fluid having improved compatibility
with an elasotmeric component may comprise adding to a major amount of a base oil
a minor amount of an additive composition having a non-dispersant viscosity index
improver.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016]
FIG. 1 illustrates torque performance of a fluid according to an embodiment as measured
using a ZF GK test rig.
FIG. 2 illustrates torque performance of a comparative fluid measured using a ZF GK
test rig.
DETAILED DESCRIPTION OF EMBODIMENTS
[0017] As power transmission fluids operate under increasingly severe conditions, the oils
used to lubricate those transmissions should be formulated to endure higher temperatures
and pressures. To reduce equipment problems and increase the interval between transmission
oil changes, the oil should be formulated so that important oil properties change
as little as possible in the face of these stresses. In particular, the shear stability
properties of the oil, which depend in great measure on the additive package, should
stay relatively constant over a wide range of temperatures and operating speeds. This
ensures smooth engagement of torque converter and shifting clutches and minimized
shudder, vibration and noise, and improved fuel economy as constant viscosity allows
good hydraulic control.
[0018] The present disclosure describes compositions and methods that provide and/or improve
anti-shudder performance of power transmission fluids, and also methods for providing
and/or improving the compatibility of lubricating fluids with elastomeric components,
for example, seals, gaskets, belts, and/or hoses. Non-dispersant viscosity index improvers
are known to improve rheological properties, such as viscosity index, of power transmission
fluids and/or lubricating fluids. Thus, the compositions of the present disclosure
provide a single solution to multiple problems, and thus an inherent cost benefit.
[0019] In an embodiment, a power transmission fluid may include a base oil and an additive
composition. The additive composition may include a non-dispersant viscosity index
improver. Non-dispersant viscosity index improvers differ from dispersant viscosity
index improvers by the absence of dispersant functional groups. A non-dispersant viscosity
index improver suitable for use in at least one of the present embodiments may comprise
a polymethacrylate, an olefin copolymer, a polystyrene, a metallocene polymer, a polymer
of a hydrogenated diene and/or a copolymer thereof with a vinyl amine, a homopolymer
of a hydrogenated conjugated diene or a copolymer thereof with a vinyl aromatic hydrocarbon,
and the like. A wide range of molecular weight polymers of the latter type can be
utilized as the base polymer of the non-dispersant viscosity index improver, and such
polymers may include linear, branched, or star-shaped configurations.
[0020] The presence of a non-dispersant viscosity index improver in the compositions and
methods of the present embodiments eliminate and/or reduce the need for conventionally
utilized friction-modifying agents or other agents for providing anti-shudder performance.
Further, inclusion of a non-dispersant viscosity index improver may improve the anti-shudder
properties of a fluid relative to a fluid including a dispersant viscosity index improver.
Embodiments may include an amount of a non-dispersant viscosity index improver sufficient
to provide and/or improve the anti-shudder characteristics of a power transmission
fluid. For example, an additive composition may comprise from about 0.01 wt% to about
50 wt% of non-dispersant viscosity index improver. As a further example, an additive
composition may comprise from about 1.0 wt% to about 25 wt% of non-dispersant viscosity
index improver. As an even further example, an additive composition may comprise from
about 3 wt% to about 15 wt% of non-dispersant viscosity index improver.
[0021] In addition, some embodiments provide and/or improve compatibility of elastomeric
components found within an automotive transmission, including an automatic and manual
transmission, a gear component, and/or an axle component. Such elastomeric components
may comprise seals, hoses, gaskets, belts, and the like. Further, these components
may be composed of elastomeric materials such as nitrile rubber, polyacrylate, silicone,
fluoroelastomers, and/or chlorinated polyethylene. Elastomeric components may deteriorate,
shrink, or fail to swell properly because of contact with certain chemicals contained
in lubricating fluids. Further, some chemicals, such as seal swell agents, may improve
the tolerance of seals and hoses to lubricating fluids. Embodiments disclosed herein
have been found to positively interact with seals and hoses to improve tensile strength
and/or elongation. Both of these factors are indicative of proper seal swell and resistance
or tolerance to deterioration. Such embodiments include a lubricating fluid comprising
a non-dispersant viscosity index improver.
[0022] The presence of a non-dispersant viscosity index improver in the compositions and
methods of the present embodiments eliminate and/or reduce the need for conventionally
utilized seal swell agents or other agents. For example, inclusion of a non-dispersant
viscosity index improver in a lubricating fluid may improve the compatibility of the
lubricating fluid with elastomeric components. In particular, this improvement may
be compared to fluids including dispersant viscosity index improvers and/or fluids
including a conventional seal swell agent.
[0023] Embodiments may include a suitable amount of a non-dispersant viscosity index improver
sufficient to provide the desired swelling and/or provide or improve the compatibility
between a lubricating fluid and elastomeric components. For example, an additive composition
may comprise from about 0.01 wt% to about 50 wt% of non-dispersant viscosity index
improver. As a further example, an additive composition may comprise from about 1.0
wt% to about 25 wt% of non-dispersant viscosity index improver. As an even further
example, an additive composition may comprise from about 3 wt% to about 15 wt% of
non-dispersant viscosity index improver.
Base Oil
[0024] Base oils suitable for use in formulating transmission fluid compositions may be
selected from any of the synthetic or natural oils or mixtures thereof. Natural oils
include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as mineral
lubricating oils such as liquid petroleum oils and solvent treated or acid-treated
mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic
types. Oils derived from coal or shale are also suitable. The base oil typically has
a viscosity of about 2 to about 15 cSt or, as a further example, about 2 to about
10 cSt at 100° C. Further, gas-to-liquid stocks are also suitable.
[0025] The synthetic base oils include alkyl esters of dicarboxylic acids, polyglycols,
and alcohols, poly-alpha-olefins, including polybutenes, alkyl benzenes, organic esters
of phosphoric acids, and polysilicone oils. Synthetic oils include hydrocarbon oils
such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes,
propylene isobutylene copolymers, etc.); poly(1-hexenes), poly-(1-octenes), poly(1-decenes),
etc. and mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes,
dinonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyl,
alkylated polyphenyls, etc.); alkylated diphenyl ethers and alkylated diphenyl sulfides
and the derivatives, analogs and homologs thereof and the like.
[0026] Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal
hydroxyl groups have been modified by esterification, etherification, etc., constitute
another class of known synthetic oils that may be used. Such oils are exemplified
by the oils prepared through polymerization of ethylene oxide or propylene oxide,
the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methylpolyisopropylene
glycol ether having an average molecular weight of about 1000, diphenyl ether of polyethylene
glycol having a molecular weight of about 500-1000, diethyl ether of polypropylene
glycol having a molecular weight of about 1000-1500, etc.) or mono- and polycarboxylic
esters thereof, for example, the acetic acid esters, mixed C
3-8 fatty acid esters, or the C
13 Oxo acid diester of tetraethylene glycol.
[0027] Another class of synthetic oils that may be used includes the esters of dicarboxylic
acids (e.g., phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic
acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic
acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids,
etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol,
etc.) Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl)sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl
phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic
acid dimer, the complex ester formed by reacting one mole of sebacic acid with two
moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid and the like.
[0028] Esters useful as synthetic oils also include those made from C
5 to C
12 monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylol
propane, pentaerythritol, dipentaerythritol, tripentaerythritol, etc.
[0029] Hence, the base oil used which may be used to make the transmission fluid compositions
as described herein may be selected from any of the base oils in Groups I-V as specified
in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines.
Such base oil groups are as follows:
Base Oil Group1 |
Sulfur (wt%) |
|
Saturates (wt%) |
Viscosity Index |
Group I |
> 0.03 |
and/or |
< 90 |
80 to 120 |
Group II |
≤ 0.03 |
And |
≥ 90 |
80 to 120 |
Group III |
≤ 0.03 |
And |
≥ 90 |
≥ 120 |
Group IV |
all polyalphaolefins (PAOs) |
Group V |
all others not included in Groups I-IV |
1Groups I-III are mineral oil base stocks. |
[0030] As set forth above, the base oil may be a poly-alpha-olefin (PAO). Typically, the
poly-alpha-olefins are derived from monomers having from about 4 to about 30, or from
about 4 to about 20, or from about 6 to about 16 carbon atoms. Examples of useful
PAOs include those derived from octene, decene, mixtures thereof, and the like. PAOs
may have a viscosity of from about 2 to about 15, or from about 3 to about 12, or
from about 4 to about 8 cSt at 100° C. Examples of PAOs include 4 cSt at 100° C poly-alpha-olefins,
6 cSt at 100° C poly-alpha-olefins, and mixtures thereof. Mixtures of mineral oil
with the foregoing poly-alpha-olefins may be used.
[0031] The base oil may be an oil derived from Fischer-Tropsch synthesized hydrocarbons.
Fischer-Tropsch synthesized hydrocarbons are made from synthesis gas containing H
2 and CO using a Fischer-Tropsch catalyst. Such hydrocarbons typically require further
processing in order to be useful as the base oil. For example, the hydrocarbons may
be hydroisomerized using processes disclosed in U.S. Pat. Nos. 6,103,099 or 6,180,575;
hydrocracked and hydroisomerized using processes disclosed in U.S. Pat. Nos. 4,943,672
or 6,096,940; dewaxed using processes disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized
and dewaxed using processes disclosed in U.S. Pat. Nos. 6,013,171; 6,080,301; or 6,165,949.
[0032] Unrefined, refined and rerefined oils, either natural or synthetic (as well as mixtures
of two or more of any of these) of the type disclosed hereinabove can be used in the
base oils. Unrefined oils are those obtained directly from a natural or synthetic
source without further purification treatment. For example, a shale oil obtained directly
from retorting operations, a petroleum oil obtained directly from primary distillation
or ester oil obtained directly from an esterification process and used without further
treatment would be an unrefined oil. Refined oils are similar to the unrefined oils
except they have been further treated in one or more purification steps to improve
one or more properties. Many such purification techniques are known to those skilled
in the art such as solvent extraction, secondary distillation, acid or base extraction,
filtration, percolation, etc. Rerefined oils are obtained by processes similar to
those used to obtain refined oils applied to refined oils which have been already
used in service. Such rerefined oils are also known as reclaimed or reprocessed oils
and often are additionally processed by techniques directed to removal of spent additives,
contaminants, and oil breakdown products.
[0033] The base oil may be combined with an additive composition as disclosed in embodiments
herein to provide a power transmission fluid. The base oil may be present in the power
transmission fluid in an amount from about 50 wt% to about 95 wt %.
Other Optional Components
[0034] The power transmission fluid may also include conventional additives of the type
used in automatic transmission fluid formulations in addition to the components described
above. Such additives include, but are not limited to, ashless dispersants, friction
modifiers, antioxidants, extreme pressure additives, corrosion inhibitors, antiwear
additives, antirust additives, metal deactivators, antifoamants, pour point depressants,
air entrainment additives, metallic detergents, and/or additional seal swell agents.
[0035] Additives used in formulating the compositions described herein can be blended into
the base oil individually or in various sub-combinations. However, it is suitable
to blend all of the components concurrently using an additive concentrate (i.e., additives
plus a diluent, such as a hydrocarbon solvent). The use of an additive concentrate
takes advantage of the mutual compatibility afforded by the combination of ingredients
when in the form of an additive concentrate simulates actual plant blending conditions.
Also, the use of a concentrate reduces blending time and lessens the possibility of
blending errors.
[0036] The power transmission fluids disclosed herein may include fluids suitable for any
power transmitting application, such as a step automatic transmission, having from
about 3 to about 7 speeds, or a manual transmission. Further, the power transmission
fluids of the present disclosure are suitable for use in transmissions with a slipping
torque converter, a lock-up torque converter, a starting clutch, and/or one or more
shifting clutches. Such transmissions include three-, four-, five-, six-, and seven-speed
transmissions, and continuously variable transmissions (chain, belt, or disk type).
They may also be used in manual transmissions, including automated manual and dual-clutch
transmissions.
EXAMPLES
[0037] Fluids tested in the following examples included the following components prepared
in the proportions disclosed below. Components that were varied are discussed with
respect to each example below. Unless otherwise specified tested samples were identical
except for varied components.
Component type |
Example 2
Proportion in Finished Fluid, wt% |
Example 2
Proportion in Finished Fluid, wt% |
Antioxidants |
0.1 - 2.5 |
0.2 - 0.5 |
Rust Inhibitors |
0 - 0.2 |
0 - 0.06 |
Thiadiazole |
0 - 2.0 |
0.01 - 0.6 |
Antifoam agents |
0 -1.5 |
0.05 - 0.20 |
Friction Modifiers |
0 - 5.0 |
0.005 - 0.25 |
Dispersant |
0 -10 |
1 - 5% |
Seal Swell Agents |
0 - 20 |
0 -10 |
Polymethacrylate viscosity index improver |
0.5-30 |
3-25 |
Basestock |
60 - 90 |
60 - 90 |
Diluent Oil |
0 - 20 |
2 - 5 |
EXAMPLE 1
[0038] Two transmission fluid formulations were tested and evaluated for effectiveness in
reducing shudder. Each fluid had identical concentrations of supplemental additives
and differed only in the types of viscosity index improver.
[0039] A polymethacrylate non-dispersant viscosity index improver was used in Formula A
at a concentration of 5.13 wt%, and a viscosity index improver with dispersant functionality
was used in Formula B at a concentration of 5.13 wt%.
[0040] As shown in Figures 1 and 2, the two automatic transmission fluids were subjected
to shudder testing by evaluating friction characteristics using the ZF GK rig. This
test was developed by ZF to measure a slip-controlled clutch's opening and closing
performance. An interchangeable intermediate shaft allows the measurement of frictional
vibration that is the basis for evaluation of "green" or initial shudder characteristics
of the test fluid. The Green Shudder portion of the "GVRK-Kurztest CFT23" consists
of a torque controlled continuous slip module, containing three 20-minute sections.
The entire sequence encompasses 60 minutes of test time. During each 20-minute section,
force is proportional to both slip speed and output torque. The result is a 0.345
m/s (50.0 rpm) constant clutch speed, with variable force to control 100Nm of output
torque, which is also constant. Each 20-minute section is analyzed for torque variation.
Due to the 1000 Hz speed data acquisition, shudder can be depicted. A 1-minute stabilization
period takes place between each continuous slip section. Test fluid temperature is
controlled at 120°C.
[0041] Measurements in Figures 1 and 2 are displayed as torque over the function of time.
The variation in torque measurements is indicative of shudder. Fluids without shudder
will display constant torque over time. Fluids with shudder will display varying torque
over time.
[0042] Shudder tests were run with a polymethacrylate non-dispersant viscosity index improver
fluid (Formula A) in Figure 1 and a dispersant viscosity index improver (Formula B)
in Figure 2. The green shudder characteristics of Formula A in Figure 1 show a reduction
in green shudder associated with the incorporation of a non-dispersant viscosity index
improver. The results using Formula A demonstrate no green shudder, as evidenced by
constant torque over time. The results using Formula B demonstrate varying torque
over time which is indicative of green shudder.
EXAMPLE 2
[0043] The incorporation of a non-dispersant viscosity index improver in a lubricating fluid
was tested for compatibility by representative elastomeric component. The component
tested was a hose composed of a chlorinated polyethylene. Table 1 demonstrates the
results obtained from the testing of several power transmission fluid with the chlorinated
polyethylene hose. The performance was determined by the tensile strength and the
elongation of the hose at the end of the test, with a more positive number indicating
better performance. Sample 1 did not contain any of non-dispersant viscosity index
improver, dispersant viscosity index improver, or seal swell agent. Sample 2 contained
an equal amount of a non-dispersant viscosity index improver and a dispersant viscosity
index improver. Sample 3 contained an equal amount of a non-dispersant viscosity index
improver and a dispersant viscosity index improver and additionally a seal swell agent.
Sample 4 contained a non-dispersant viscosity index improver and a seal swell agent.
All other components in the fluids tested were identical.

[0044] The results shown in Table 1 show that Sample 4, which contained non-dispersant viscosity
index improver, demonstrated superior tensile strength compared to samples having
less or no non-dispersant viscosity index improver. Furthermore, the incorporation
of a seal swell agent to Samples 3 and 4 did not provide a significant benefit. Notably,
the benefit achieved through the use of solely the non-dispersant viscosity index
improver greatly exceeded that achieved by the mixed formulation with or without the
seal swell agent.
[0045] At numerous places throughout this specification, reference has been made to a number
of U.S. Patents. All such cited documents are expressly incorporated in full into
this disclosure as if fully set forth herein.
[0046] Other embodiments will be apparent to those skilled in the art from consideration
of the specification and practice of the invention disclosed herein. As used throughout
the specification and claims, "a" and/or "an" may refer to one or more than one. Unless
otherwise indicated, all numbers expressing quantities of ingredients, properties
such as molecular weight, percent, ratio, reaction conditions, and so forth used in
the specification and claims are to be understood as being modified in all instances
by the term "about." Accordingly, unless indicated to the contrary, the numerical
parameters set forth in the specification and claims are approximations that may vary
depending upon the desired properties sought to be obtained by the present invention.
At the very least, and not as an attempt to limit the application of the doctrine
of equivalents to the scope of the claims, each numerical parameter should at least
be construed in light of the number of reported significant digits and by applying
ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations, the numerical values
set forth in the specific examples are reported as precisely as possible. Any numerical
value, however, inherently contains certain errors necessarily resulting from the
standard deviation found in their respective testing measurements. It is intended
that the specification and examples be considered as exemplary only, with a true scope
and spirit of the invention being indicated by the following claims.
1. A lubricating fluid having compatibility with an elastomeric component, including:
(a) a major amount of a base oil; and
(b) a minor amount of an additive composition having at least one non-dispersant viscosity
index improver.
2. The fluid of claim 1, wherein the fluid further promotes swelling of the elastomeric
component.
3. The fluid of any one of claims 1-2, wherein the non-dispersant viscosity index improver
includes a polymethacrylate viscosity index improver.
4. The fluid of any one of claims 1-3, wherein the non-dispersant viscosity index improver
is present in an amount from 0.01 wt% to 50 wt% in the additive composition.
5. The fluid of any one of claims 1-3, wherein the non-dispersant viscosity index improver
is present in an amount from 1 wt% to 25 wt% in the additive composition.
6. The fluid of any one of claims 1-3, wherein the non-dispersant viscosity index improver
is present in an amount from 3 wt% to 15 wt% in the additive composition.
7. The fluid of any one of claims 1-6, wherein the base oil includes one or more of a
natural lubricating oil, a synthetic lubricating oil, and a mixture thereof.
8. The fluid of any one of claims 1-7, wherein the fluid is free of a dispersant viscosity
index improver.
9. The fluid of any one of claims 1-8, wherein the fluid is suitable for use in an automatic
transmission, a continuously variable transmission, a slipping torque converter, a
step automatic transmission, a clutch-to-clutch transmission, and a transmission with
a wet starting clutch.
10. The fluid of any one of claims 1-9, wherein the elastomeric component includes one
or more of a seal, a hose, a gasket, and a belt.
11. The fluid of any one of claims 1-10, wherein the elastomeric component is composed
of any one of a chlorinated polyethylene, a nitrile rubber, a polyacrylate, a fluoroelastomer,
and a silicone.
12. The fluid of any one of claims 1-11, wherein the compatibility of the fluid with an
elastomeric component is improved relative to a fluid free of a non-dispersant viscosity
index improver.
13. The fluid of any one of claims 1-11, wherein the compatibility of the fluid with an
elastomeric component is improved relative to a fluid free of a non-dispersant viscosity
index improver and containing a dispersant viscosity index improver.
14. The fluid of any one of claims 1-13, wherein the fluid further contains a seal swell
agent.
15. The fluid of any one of claims 1-14, wherein the lubricating fluid is a power transmitting
fluid, and the power transmitting fluid provides improved anti-shudder performance
relative to a power transmitting fluid free of at least one non-dispersant viscosity
index improver and containing a dispersant viscosity index improver.
16. An automatic transmission lubricated with the fluid of claim 15.
17. The automatic transmission of claim 16, wherein the transmission is a continuously
variable transmission.
18. A method of lubricating a power transmission having an elastomeric component, including
the steps of adding to, and operating in said power transmission, a fluid as set forth
in any one of claims 1-15.
19. A method of improving the anti-shudder capabilities of a power transmission fluid,
including the step of:
lubricating a power transmission with a power transmission fluid as claimed in claim
15.
20. A method of improving the torque performance of a power transmission, including the
step of:
lubricating a power transmission with a power transmission fluid as claimed in claim
15.
21. A method of promoting seal swell of an elastomeric seal, including the step of lubricating
the elastomeric seal with a lubricating fluid as claimed in any one of claims 1-14.
22. A method of making a power transmitting fluid as claimed in claim 15, having anti-shudder
capability, including the step of adding to a major amount of a base oil, a minor
amount of an additive composition having a non-dispersant viscosity index improver.
23. A method of making a lubricating fluid as claimed in any one of claims 1-14, having
improved compatibility with an elastomeric component, including the step of adding
to a major amount of a base oil, a minor amount of an additive composition having
a non-dispersant viscosity index improver.