Gear Lubricants
Product Data
castrol.com/GPS
800 255 4417
May 2025
GPS
Castrol
®
Alpha™ HC
-38 -20
-2
14 32
Brookfield
Viscosity
(cP)
Temperature (ϒF)
100,000
80,000
60,000
40,000
20,000
0
Mineral Oil
Cold Temperature Performance
ASTM D 2983 (Air Bath) Procedure
Castrol Alpha HC
Commercial Synthetic
ISO Grade Method Unit 32 46 68
Viscosity @40°C, cSt ASTM D445 mm
2
/s 32.6 45.7 67.8
Viscosity @100°C, cSt ASTM D445 mm
2
/s 6.08 7.85 10.4
Viscosity @100°F ASTM D2161 SUS 153 217 341
Viscosity @210°F ASTM D2161 SUS 46.1 51.9 61.5
Viscosity Index ASTM D2270 -- 136 138 140
FZG Gear Test, load stage ASTM D5182 Stages -- -- --
Pour Point ASTM D97 °C (°F) -45(-49) -45(-49) -45(-49)
Flash Point, open cup method ASTM D92 °C (°F) 228(442) 228(442) 228(442)
API Gravity ASTM D287 -- 36.5 35.1 35.4
Specific Gravity @16°C/60°F ASTM D1298 -- 0.842 0.844 0.8428
Pounds per Gallon ASTM D287 -- 7.01 7.03 7.06
150 220 320 460
Viscosity @40°C, cSt 149.2 220.8 319.4 458.2
Viscosity @100°C, cSt 18.9 25.6 32.3 41.2
Viscosity @100°F, SUS 691 1,021 1,480 2,122
Viscosity @210°F, SUS 93.8 122.8 152.9 193.5
Viscosity Index 143 148 141 139
FZG Gear Test, load stage >12 >12 >12 >12
Pour Point, °C (°F) -45(-49) -45(-49) -45(-49) -45(-49)
Flash Point, open cup method 227(441) 227(441) 227 (441) 227 (441)
APO Gravity 33.4 33.0 32.4 31.0
Specific Gravity @16°C/60°F 0.858 0.860 0.863 0.870
Pounds per Gallon 7.14 7.16 7.18 7.25
E15
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