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CRO 10W40 Competition Break-In Oil

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12.00 LBS
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CRO 10W40 Competition Break-In Oil

  • Mineral oil
  • Protects engine components and speeds up the break-in process
  • Race/high performance engines should not be broken in on fully or semi-synthetic oils


Competition break-in oil. Advanced formula of high quality solvent refined conventional oils fortified with special low volatility components and appropriate additive treatment.

Use as received engine break-in. May also be used for light operational duties up to 500 miles. Developed for modified gasoline and diesel engines.


  • CRO 10w40 is formulated to meet the needs of the professional engine builder.
  • Maximizes power output by optimizing break-in process.
  • CRO 10w40 provides full protection of highly stressed components whilse allowing optimum break-in process for piston rings and bore.
  • CRO 10w40 additive technology enables full load runs for short bursts.
  • The viscosity modifiers selected ensure that even though the additive system performance is strong the pistons can achieve satisfactory boundary lubrication for breaking-in purposes.


  • Suitable for 5 hours dynamometer running or 500 miles on road.
  • Optimum oil temperature 185-240°F.
  • Very low leak down [4%] after controlled break-in.

SAE Viscosity Grade ... 10w40
Specific Gravity @ 59°f ... 0.879
Kinematic Viscosity @ 212°F ... 13.7cSt
Kinematic Viscosity @ 104°F ... 96cSt
Viscosity Index ... 140
Pour Point °F ... -13
Flashpoint °F ... 329
Cold Crank Viscosity @ -13°F ... 7,000cP 

Health and Safety Data Sheet 5736 applies to this product. When used for the purpose recommended and with due regard to the appropriate Health and Safety Data, the product should cause no concern. If in doubt, consult with Millers Oils Technical Department.