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Castrol R40 - Racing Engine Oils - 1948

Castrol R40 - Racing Engine Oils - 1948


Castrol R40 is a castor-based lubricant containing specially prepared additives to prevent rapid deterioration through oxidation. Its superior oiliness over mineral oils, imparted by the chemical structure of its components, gives it a great affinity for hot surfaces and provides excellent load-carrying properties which is an important consideration with highly stressed engines running at peak revolutions.



Although Castrol R40 is primarily designed for the racing world, its unique properties can also benefit the private owner interested in really high performance.

When selecting an engine lubricant for sports cars, modified saloons or high performance motorcycles, it must not be assumed that a special oil is always necessary. In the vast majority of cases the well-known, widely available brands of Castrol motor oil are entirely satisfactory for racing, and most modified and tuned production vehicles will operate perfectly well on these. Where special camshafts are fitted though, there may be a case for using Castrol R40 as the small areas in contact will be heavily loaded especially where double valve springs are fitted.

For racing and high speed rallying, however, Castrol R40 does provide the ultimate in lubrication in return for extra cost. If the best possible performance coupled with reliability is the aim, then the remarkable stamina and great film strength of Castrol R40 will provide a valuable 'margin of safety' at ultra high engine speeds and temperatures.



  • Unique properties
  • Remarkable stamina and great film strength


Never mix Castrol R40 with mineral based oils. It should always be remembered that Castrol R40 will not mix with conventional mineral or synthetic crankcase oil. When changing from one type to the other, Castrol Solvent Flushing Oil must be used in accordance with the recommended changeover procedure.


Pack sizes available - 12x1ltr, 4x4ltr

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