Millers CRO 10w40 Competition Break-In Oil

Millers Oils
M7981-5 L
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CRO 10w40


Competition running in oil for test bed running up to 4 hours. Advanced formulation of high quality solvent refined mineral oils fortified with special low volatility components and appropriate additive treatment. A 10w40 viscosity grade mineral oil which has been carefully formulated to offer an extremely high protection level to new engine components and speed up the bedding in process. Ideally suited for test bed running.


Use as received for test bed running.

May also be used for light operational duties up to 500 mls/800kms.

Developed for modified petrol and diesel engines.


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


  • Suitable for 5 hours test bed running or 500mls/800km on road
  • Optimum oil temperature 85-115oC
  • Very low leak down after controlled test bed running


SAE Viscosity Grade                                    10w40

Specific Gravity @ 15°C                               0.871

Kinematic Viscosity @ 100°C                        13.6cSt

Kinematic Viscosity @ 40°C                          89.8cSt

Viscosity Index                                            154

Pour Point °C                                              <-25

Flashpoint °C                                               >200

Cold Crank Viscosity @ -25°C                        7,000cP Maximum