Millers Oils Motorsport Competition Running In Oil – 5L (7981)
Essential Protection for New or Rebuilt Engines
Give your engine the best possible start with Millers Oils Motorsport Competition Running In Oil. Specially formulated for newly rebuilt engines, this mineral-based running-in oil helps critical components “bed in” properly, preventing long-term wear and bore glazing — and ensuring peak performance when it matters most.
Key Features:
- Purpose-Built for Running In: Ensures correct bedding-in of piston rings, crankshaft bearings, valve trains, and more.
- Superior Protection: Reduces wear, maintains stable oil pressure, and prevents bore glazing.
- Maximum Power & Torque: Engine is optimally conditioned to deliver full performance after running-in.
- Lower Oil Consumption: Helps seal rings properly for long-term engine efficiency.
- Motorsport Proven: Designed for high-stress environments and professional use.
Typical Applications:
- Motorsport engines, high-performance rebuilds, and track cars
- Use on a rolling road, test bed, or on-road running-in (up to 500 miles / 800 km)
Running In Procedure (Important):
✅ Fill the engine with Millers Oils Motorsport Competition Running In Oil to the maximum mark on the dipstick.
✅ Operate the engine at peak torque for approximately 500 miles on the road or use on a test bed/rolling road.
✅ Monitor for successful completion indicators:
- Compression ratio matches manufacturer’s specifications
- Noticeable increase in engine performance (e.g., better acceleration)
- Improved fuel efficiency
- Reduced oil consumption
Important Disclaimer:
- DO NOT use fully synthetic or semi-synthetic oils during the running-in process, as this can cause bore glazing and prevent proper bedding-in of components.
- Millers Oils provides general guidance, but it is the responsibility of the engine builder to ensure that the correct procedure is carried out according to engine type and specifications.
Technical Specifications:
- Product Code: 7981
- Oil Type: Mineral, multi-viscosity
- Density @ 15°C: 0.870 g/ml
- Viscosity @ 100°C: 14.1 cSt
- Flashpoint: >220°C
Recommended Companion Products:
- Millers Oils Assembly Lubricant (Part Code 7982) – Apply to vital components like cam lobes during rebuild for maximum protection at initial start-up.
Trust Millers Oils Motorsport Competition Running In Oil to protect your rebuild and deliver maximum long-term performance.
Order now from Cox Motor Parts — Official Millers Oils Specialist!
Frequently Asked Questions (FAQ)
How long should I run in a rebuilt engine with Millers Oils Motorsport Competition Running In Oil?
We recommend running the engine at peak torque for approximately 500 miles (800 kilometers) if running on the road, or equivalent on a test bed or rolling road. After completing the running-in procedure, you can switch to your preferred fully synthetic or semi-synthetic performance oil.
Can I use fully synthetic oil to run in my engine?
No.
Using fully synthetic or semi-synthetic oils during the running-in phase can lead to bore glazing, which prevents piston rings from bedding in properly. Always use a dedicated mineral-based running-in oil like Millers Oils Motorsport Competition Running In Oil until the process is complete.
What are the signs that my engine has been properly run in?
Successful running-in is indicated by:
- Compression ratios meeting manufacturer specifications
- Improved engine performance (e.g., stronger acceleration)
- Better fuel efficiency
- Reduced oil consumption
Should I use an assembly lubricant when rebuilding an engine?
Yes.
For maximum protection during first start-up, we recommend using Millers Oils Assembly Lubricant (Part Code 7982) on critical components like cam lobes, bearings, and other friction points before adding the running-in oil.
Need more expert advice?
Contact our team at Cox Motor Parts — we’re here to help you get the best from your engine!
