CRO 10W40 is a motorsport oil designed to specifically to aid the running in process of rebuilt engines by providing full protection of highly stressed components whilst allowing optimum bedding in process for piston rings to the cylinder bore. It is not recommended that synthetic or semi synthetic oils are used for bedding in as they can be too slippery.Specifically developed for running in newly built enginesProtects whilst allowing correct piston ring beddingPrevents bore glazing and high blow-by This is a blend of high quality solvent refined mineral oils.Suitable for test bed running up to 5 hours or for 500 miles on the road CRO 10W40 also allows for short burst runs at full engine load.It is recommended that once the running in process is complete, the oil system is flushed and the oil replaced with the correct grade specified for the engine.Technical Data Sheet