From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Test results and evaluation of Shell 'siper' light racing oil compared to other compound and fatty oils.
| Identifier | ExFiles\Box 144\1\ scan0114 | |
| Date | 24th October 1925 | |
| HL. To BY.{R.W. Bailey - Chief Engineer} and ME. from R.{Sir Henry Royce} c. to CJ. Hs.{Lord Ernest Hives - Chair} X967 R2/M24.10.25. LUBRICATING OIL X.1588 X.967 X.1583 Thank you for examining the Shell siper light racing oil. It would seem that this has not very much to recommend it in preference to the thinner compound oils we have been obtaining from the Price Co. It is just possible however that the mineral oil is of a very high quality, and that the fatty oils, which we probably may conclude are Castor a and Sperm oil, may also be superior to the fatty oils used to compound Price's or Wakefield's oil. The result of my tests of this oil on the small engine here is that it not only gave slightly more power than any other oil we have used, but the wear and gas-tightness of the engine seem to be excellent. I am very much against the use of the thick oils we were in the habit of using in both engines and gearboxes. R.{Sir Henry Royce} | ||