Castrol Optigear EP 68
ISO VG 68 gear oil
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Key specs
| Spec | Value | Method |
|---|---|---|
| KV40 | 68 cSt | ASTM D445 |
| KV100 | 8.9 cSt | ASTM D445 |
| Viscosity index | 102 | ASTM D2270 |
| Pour point | -27 °C | ASTM D97 |
| Flash point | 240 °C | ASTM D92 |
| Density at 15 °C | 0.885 g/cm³ | typical |
Grade checks
- KV40 is inside ISO VG 68 (61.2–74.8 cSt).
- Computed viscosity index is 104, within 2 points of the listed 102.
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
- Synthetic: Conventional
- AGMA class: AS
- FZG fail stage: >=12
- Copper: 1
- Note: Extreme pressure gear lubricant, mineral oil
Equivalents
| Oil | Score | Why |
|---|---|---|
| Mobil 600 XP 68 | 74 | same ISO 68, VI 101 vs 102, conventional, pour -27 vs -27, flash within 15 °C, AGMA AS, buyable now |
| Chevron Meropa 68 | 74 | same ISO 68, VI 101 vs 102, conventional, pour -32 vs -27, flash within 15 °C, AGMA AS, buyable now |
| Shell Omala S2 G 68 | 72 | same ISO 68, VI 99 vs 102, conventional, pour -24 vs -27, flash within 15 °C, AGMA AS, buyable now |
| Shell Omala S2 GX 68 | 68 | same ISO 68, VI 100 vs 102, conventional, pour -24 vs -27, flash within 15 °C, AGMA AS |
| Chevron Meropa XL 68 | 47 | same ISO 68, VI 110 vs 102, conventional, 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 EP, viscosity index calculator, ISO / SAE / AGMA chart.
Questions
Is Castrol Optigear EP 68 an ISO VG 68 oil?
Yes. The catalogue lists it as ISO VG 68, which is a kinematic viscosity of 68 cSt at 40 °C, plus or minus 10 percent (61.2 to 74.8 cSt). Confirm the current data sheet before you fill a machine.
What is a Castrol Optigear EP 68 equivalent?
Published oils in the same application and grade include Mobil 600 XP 68, Chevron Meropa 68, Shell Omala S2 G 68. 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 EP 68 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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