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).
Letter to Price's Lubricants Ltd. explaining the decision to use viscosity numbers over grade letters in instruction books.
| Identifier | ExFiles\Box 144\1\ scan0288 | |
| Date | 14th March 1938 | |
| 1225 Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}4/MH.{M. Huckerby} 14th. March 1938. Messrs. Price's Lubricants Ltd., Belmont Works, Battersea, LONDON. S.W.11. For the attention of Mr.Brooker. Dear Sirs, We thank you for your letter of March 11th. We are not in agreement with your suggestion to put in the grade letters as well as the viscosity numbers. As you know you have recently changed Motorine M from SAE.40 to SAE.30. If, therefore, we had mentioned the viscosity in the instruction books six months ago they would now be wrong. The reason for our wishing to use viscosity numbers only, is so that our instruction books shall recommend a suitable oil for old cars as well as new cars, and so that no change of grade letters by manufacturers to suit the selling conditions can render the instruction books wrong. Some of the oil Companies have already agreed to our suggestion. Yours faithfully, for ROLLS-ROYCE LTD. | ||