AMSOIL Synthetic Gear Lube Outperforms Valvoline
Gear Lube
High quality gear oils must lubricate, cool and protect geared systems. They must
also carry damaging wear debris away from contact zones and muffle the sound of
gear operation. Commonly used in differential gears and standard transmission applications
in commercial and passenger vehicles, as well as a variety of industrial machinery,
gear oils must offer extreme temperature and pressure protection in order to prevent
wear, pitting, spalling, scoring, scuffing and other types of damage that result
in equipment failure and downtime. Protection against oxidation, thermal degradation,
rust, copper corrosion and foaming is also important.
AMSOIL submitted its 75W-90 Synthetic Gear Lube (AGR) and Valvoline 75W-90 Gear
Lube to an independent laboratory for quality comparison tests. The gear lubes were
tested according to ASTM testing procedures in several critical performance areas,
including oxidation resistance, viscosity retention and cold temperature fluidity.
Oxidation resistance was measured using the L-60-1 Thermal Oxidation Stability Test,
viscosity retention was measured using the KRL Shear Stability Test and cold temperature
fluidity was measured using the Brookfield Viscosity Test. Additional load carrying,
wear, extreme pressure and scoring protection tests were performed exclusively on
AMSOIL 75W-90 Synthetic Gear Lube using the L-37 High Torque Axle Test and the L-42
High Speed Axle Test.
L-60-1 Thermal Oxidation Stability Test
Test Conditions
The L-60-1 Thermal Oxidation Stability Test measures a lubricant's rate
of deterioration under severe oxidation conditions. A measured sample of test lubricant
is placed in a special gear case with two spur gears and a copper catalyst strip.
The gears are driven at 1,725 rpm at 163°C for a 50-hour duration, while air is
bubbled through the sample.
Viscosity increase, deposits not soluble in pentane or
toluene, carbon varnish and sludge deposits are measured upon test completion. Test
specifications are listed below.
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L-60-1 Thermal Oxidation Stability Test Specifications
|
|
|
API GL-5 |
API MT-1/SAE J-2360/
MIL-PRF-2105E/Mack GO-J |
Mack GO-J+ |
|
Test Conditions |
50 hours @ 163°C |
50 hours @ 163°C |
100 hours @ 163°C |
|
Viscosity Rise, % |
100 Max. |
100 Max. |
100 Max. |
|
Pentane Insolubles, % |
3 Max. |
3 Max. |
3 Max. |
|
Toluene Insolubles, % |
2 Max. |
2 Max. |
2 Max. |
|
Carbon Varnish, rating |
Not required |
7.5 Min. |
7.5 Min. |
|
Sludge, rating |
Not required |
9.4 Min. |
9.4 Min. |
|
L-60-1 Thermal Oxidation Stability Test Results
|
|
|
AMSOIL Synthetic
75W-90
|
Valvoline
75W-90 |
Valvoline
75W-90 |
|
Test Conditions |
100 hours @ 163°C |
50 hours @ 163°C |
100 hours @ 163°C |
|
Viscosity Rise, % |
25.17 |
17.50 |
38.50 |
|
Pentane Insolubles, % |
0.20 |
0.87 |
1.17 |
|
Toluene Insolubles, % |
0.13 |
1.11 |
0.99 |
|
Carbon Varnish, rating |
8.0 |
7.2 |
5.9 |
|
Sludge, rating |
9.5 |
9.4 |
9.4 |
Test Results
Because AMSOIL 75W-90 Synthetic Gear Lube is a premium lubricant designed for extended
drain service, the test was allowed to continue for 100 straight hours, double the
standard test length. The Valvoline 75W-90 was run at both the standard 50-hour
test length and the double 100-hour test length. Test results indicate AMSOIL 75W-90
Synthetic Gear Lube outperformed Valvoline at both test lengths.
Even at double the standard test length, AMSOIL 75W-90 scored almost four times
better than industry test specifications in the area of viscosity increase, while
also greatly exceeding specifications in all areas of the test.
The photographs below show the superior deposit-control characteristics of AMSOIL
75W-90 Synthetic Gear Lube.
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L-60-1 Thermal Oxidation Stability Test Results
|
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AMSOIL 75W-90 (100 hours)
|
Valvoline 75W-90 (100 hours)
|
Valvoline 75W-90 (50 hours)
|
|
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Even after enduring a double-length, 100-hour L-60-1 Thermal Oxidation
Stability Test, AMSOIL 75W-90 Synthetic Gear Lube produced significantly fewer deposits
than the Valvoline 75W-90 run at a standard, 50-hour test.
KRL Shear Stability Test
Test Conditions
It is essential that high-quality gear lubes resist shear to ensure adequate oil
film thickness and protection against friction and wear. The KRL Shear Stability
Test is used to determine the mechanical shear stability of lubricants containing
polymer. Mandatory under the SAE J-306 gear oil standard, the KRL Shear Stability
Test makes use of a taper roller bearing in order to shear the test fluid and determine
the permanent drop in viscosity caused by the mechanical stress under practical
conditions. Under the specifications of SAE J- 306, the measured viscosity at 100°C
(212°F) of an SAE 90 gear oil must exceed 13.5 cSt after 20 hours of testing.
Test Results
AMSOIL 75W-90 Synthetic Gear Lube easily exceeded SAE J-306 specifications following
the 20-hour test length and was allowed to continue for a total of 192 straight
hours, almost 10 times longer than the standard test length. Even after this extended
test, AMSOIL 75W-90 lost only 0.40 percent of its original viscosity, making it
99.6 percent shear stable.
Valvoline 75W-90 Gear Lube, on the other hand, failed the test during the initial
20-hour testing period, losing 14 percent of its original viscosity.
Brookfield Viscosity Test
Test Conditions
The Brookfield Viscosity Test (ASTM 0-2983) is used to determine the interna
l fluid-friction of a lubricant during cold temperature operation. The lubricant
sample is chilled in a -40°C (-40° F) air bath for 16 hours, and a Brookfield viscometer
determines the torque required to shear the lubricant. The lower the cold temperature
viscosity (measured in centipoise), the better the cold temperature protection.
ASTM specifications dictate that 75W-90 gear oils measure less than 150,000 cP at
test completion.
Test Results
AMSOIL 75W-90 Synthetic Gear Lube easily passed the Brookfield Viscosity Test, measuring
88,000 cP at test completion, 42 percent less than test limits. The superior cold
temperature properties of AMSOIL 75W-90 Synthetic Gear Lube ensure quicker oil flow,
enhanced component protection and improved fuel efficiency.
Many conventional lubricants fail to pass the Brookfield Viscosity Test due to the
paraffinic (wax) content in their base oils. Valvoline Gear Lube passed the test
at 130,000 cP, only 13 percent lower than test limits.
|
KRL Test Results |
AMSOIL 75W-90
(After 192 hrs. KRL) |
Valvoline 75W-90
(After 20 hrs. KRL) |
|
Beginning Viscosity @ 100°C (cSt) |
15.09 |
14.46 |
|
Ending Viscosity @ 100°C (cSt) |
15.03 (pass) |
12.42 (fail) |
|
% Viscosity Loss, 100°C |
0.40% |
14.10% |
1-37 High Torque Axle Test
Test Conditions
The L-37 High Torque Axle Test is used to evaluate a gear lubricant's load-carrying,
wear and extreme pressure characteristics in hypoid gears operating under both high-speed/low-torque
and low-speed/high-torque conditions. A Dana Model 60 hypoid gear axle is used with
either coated or uncoated drive gear and pinion to drive two dynamometers from an
eight-cylinder, 5.7-liter gasoline engine. With the axle filled with the test lubricant,
the high-speed/low-torque test is performed for 100 minutes, with the gears visually
assessed afterwards. Next, the low-speed/high-torque test is run for 24 hours, followed
by a thorough inspection of the gears. Performance relative to API GL-5 and MIL-
PRF-2105E
specifications is assessed based on tooth
surface rippling, ridging, pitting and
wear, deposits and discoloration.
The gears protected by AMSOIL 75W-90
Synthetic gear Oil showed little or no
rippling, ridging, pitting or deposits
following the L-37 High Torque Axle Test.
Test Results
Testing on AMSOIL 75W-90 Synthetic Gear Oil was conducted using uncoated gear and
pinion. The AMSOIL lubricant passed on all counts and showed little to no rippling,
ridging, pitting or deposits, indicating that AMSOIL 75W-90 provides superior protection
and performance under extreme pressure conditions.
L-42 High Speed Axle Test
Test Conditions
The L-42 High Speed Axle Test evaluates the antiscoring characteristics of a
gear
lubricant operating under high-speed and shock-loading conditions. A Spicer Model
44-1 hypoid gear axle is driven by a 5.7 liter, V8
The gears protected by AMSOIL 75W-90
Synthetic gear Oil showed little to no scoring
following the L-42 High Speed Axle Test.
gasoline engine with a four-speed
truck transmission and two high-inertia dynamometers and hard accelerated to 100
mph. The axle is periodically shock-loaded through a dynamometer to simulate high
shock-loading conditions. The axle is accelerated through the gears to 1,050 r/min
and decelerated to 530 r/min. This cycle is repeated five times, followed by 10
shock loadings. In order to meet API GL-5 and MIL-PRF-2105E gear oil specifications,
scoring must be equal to or better than gears tested with a reference oil.
Test Results
AMSOIL 75W-90 Synthetic Gear Oil easily passed the L-42 High Speed Axle Test, receiving
a significantly better rating than the reference oil and leaving little to no scoring
on the ring and pinion.
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L-42 High Speed Axle Test
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AMSOIL 75W-90
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Reference Oil
|
|
Ring |
13
|
19
|
|
Pinion |
18
|
27
|