Castrol Optigear 1100/320
ISO VG 320 extreme pressure gear oil
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Key specs
| Spec | Value | Method |
|---|---|---|
| KV40 | 317 cSt | ASTM D445 |
| KV100 | 23.6 cSt | ASTM D445 |
| Viscosity index | 95 | ASTM D2270 |
| Pour point | -21 °C | ASTM D97 |
| Flash point | 250 °C | ASTM D92 |
| Density at 15 °C | 0.912 g/cm³ | typical |
Grade checks
- KV40 is inside ISO VG 320 (288–352 cSt).
- Computed viscosity index is 94, within 2 points of the listed 95.
Viscosity and temperature
ASTM D341 (Walther) fitted to the published KV40 and KV100. It is an interpolation between those two points, and it is not meaningful below the pour point. Move the control to read a temperature.
Classification
- Category: Gear
- Attribute: Extreme Pressure
- Synthetic: Conventional
- AGMA class: AS
- FZG fail stage: >=14
- Copper: Unlisted
- Note: Extreme pressure gear lubricant
Sulfur, EP additives and yellow metal
Extreme-pressure gear oils use sulfur compounds so steel teeth do not weld under shock. That same sulfur can tarnish or pit copper, brass and bronze: a bronze worm wheel, a brass cage, a cooler tube. ASTM D130 sits a polished copper strip in the oil and scores the colour. 1A and 1B are the ratings to keep when yellow metal shares the oil. The strip below is that test at room temperature.
How lubricant-induced copper corrosion works
Equivalents
| Oil | Score | Why |
|---|---|---|
| Mobil 600 XP 320 | 98 | same ISO 320, VI 97 vs 95, additive ep, conventional, pour -24 vs -21, flash within 15 °C, AGMA AS, buyable now |
| Mobil EP 320 | 93 | same ISO 320, VI 97 vs 95, additive ep, conventional, pour -24 vs -21, flash within 15 °C, AGMA AS |
| Chevron Meropa 320 | 92 | same ISO 320, VI 98 vs 95, additive ep, conventional, pour -22 vs -21, AGMA AS, buyable now |
| Shell Omala S2 GX 320 | 92 | same ISO 320, VI 98 vs 95, additive ep, conventional, pour -15 vs -21, flash within 15 °C, AGMA AS |
| Shell Omala S2 G 320 | 90 | same ISO 320, VI 100 vs 95, additive ep, conventional, pour -15 vs -21, flash within 15 °C, AGMA AS |
Scores use published typical data. This is not an exact equivalent, and it is not an OEM approval. Confirm the substitute with the machine builder.
Documents
- Product data sheet
- Safety data sheet
- Specs last read from the data sheet on 2026-09-09.
Related: Castrol, Optigear 1100, viscosity index calculator, ISO / SAE / AGMA chart.
Questions
Is Castrol Optigear 1100/320 an ISO VG 320 oil?
Yes. The catalogue lists it as ISO VG 320, which is a kinematic viscosity of 320 cSt at 40 °C, plus or minus 10 percent (288 to 352 cSt). Confirm the current data sheet before you fill a machine.
What is a Castrol Optigear 1100/320 equivalent?
Published oils in the same application and grade include Mobil 600 XP 320, Mobil EP 320, Chevron Meropa 320. The match is from typical data-sheet values, not from an OEM approval. It is not an exact equivalent. Confirm the substitute with the machine builder.
Can Castrol Optigear 1100/320 be mixed with another oil?
Mixing two oils that share a base family is sometimes done and sometimes a mistake. Do not mix this oil with a PAG. For any other mix, follow the maker's change-over guidance and the machine manual.
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