Castrol Optigear BM 68
ISO VG 68 extreme pressure gear oil
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Key specs
| Spec | Value | Method |
|---|---|---|
| KV40 | 68 cSt | ASTM D445 |
| KV100 | 9.1 cSt | ASTM D445 |
| Viscosity index | 110 | ASTM D2270 |
| Pour point | -24 °C | ASTM D97 |
| Flash point | 220 °C | ASTM D92 |
| Density at 15 °C | 0.89 g/cm³ | typical |
Grade checks
- KV40 is inside ISO VG 68 (61.2–74.8 cSt).
- Computed viscosity index is 109, within 2 points of the listed 110.
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: >=12
- Copper: Unlisted
- Note: For spur and bevel gear units, including severe operating conditions
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 68 | 91 | same ISO 68, VI 101 vs 110, additive ep, conventional, pour -27 vs -24, flash within 15 °C, AGMA AS, buyable now |
| Chevron Meropa XL 68 | 85 | same ISO 68, VI 110 vs 110, additive ep, conventional, flash within 15 °C, AGMA AS |
| Shell Omala S2 GX 68 | 85 | same ISO 68, VI 100 vs 110, additive ep, conventional, pour -24 vs -24, flash within 15 °C, AGMA AS |
| Shell Omala S2 G 68 | 84 | same ISO 68, VI 99 vs 110, additive ep, conventional, pour -24 vs -24, AGMA AS, buyable now |
| Chevron Meropa 68 | 76 | same ISO 68, VI 101 vs 110, additive ep, conventional, AGMA AS, buyable now |
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 BM, viscosity index calculator, ISO / SAE / AGMA chart.
Questions
Is Castrol Optigear BM 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 BM 68 equivalent?
Published oils in the same application and grade include Mobil 600 XP 68, Chevron Meropa XL 68, Shell Omala S2 GX 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 BM 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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