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Millers Oils CRO 10W-40 Competition Running In Oil

Millers Oils CRO 10W-40 Competition Running In Oil

Millers CRO 10w40 Running In - 1 Litre

1 Litre


Millers CRO 10w40 Running In - 5 Litres

5 Litres


Millers CRO 10w40 Running In - 20 Litres

20 Litres


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  • Description
  • Benefits
  • Specifications
  • Shipping Explained

Millers Oils CRO 10W-40 Competition Running In Oil

Millers Oils CRO 10W-40 is a competition running in oil for test bed running for up to 4 hours. It features an advanced formulation of high quality solvent refined mineral oils fortified with special low volatility components and appropriate additive treatment. This 10w40 viscosity grade mineral oil 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. May also be used for light operational duties up to 500mls/800kms. Developed for modified petrol and diesel engines.

PDF Downloads:

Download the Technical PDFDownload the Safety PDF


  • Formulated to meet the needs of the professional engine builder
  • Maximises power output by optimising bedding in process
  • Provides full protection of highly stressed components whilst allowing optimum bedding in process for piston rings and bore
  • 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/800kms on road
  • Optimum oil temperature 85-115°C
  • Very low leak down [4%] after controlled test bed running


SHIPPING IS FREE* for orders of £75 and over , regardless of the weight of your order.
We've tried to keep all other shipping costs as low as we can.

Carriage starts at just £0.95 (inc VAT) for small items, with our most common courier rate set at £4.99 for orders of 5kg (enough for 5 litres of oil).

  • *Free shipping is available for UK Royal Mail, UPS Access Point™ (click & collect) and standard UK courier services (not express / priority / islands).
  • Courier surcharges mean we are unable to offer free "to the door" courier shipping from us in Cornwall up to Highlands / Grampian in Scotland - and because we send a lot of liquids, not every courier option is available to us. UPS Access Point™ (click & collect) is available as a free shipping option across Scotland, Wales and England, wherever there is a UPS Access Point™ Location.
  • Carriage charges are based on weight - please see our table of carriage costs for full details (although adding an item to your cart and viewing the calculated carriage is often easier!).
  • Priority shipping is also available.

How long will it take to get my order?

We give an estimate of delivery dates as you shop and in your basket. The vast majority of items are held in stock and dispatched from our UK warehouse and we'll do all we can to get your order to you as quickly as possible.

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Brand: Millers Oils
Oil Type: Mineral

We say...

"The only dedicated running in oil we have... and a damn good one it is too, suitable for running in competition engines on dyno etc."

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