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).
Internal memorandum updating oil draining intervals for vehicles fitted with 'General' filters.
| Identifier | ExFiles\Box 136\3\ scan0023 | |
| Date | 14th December 1938 | |
| 1139 To Hd.{Mr Hayward/Mr Huddy} c. to By.{R.W. Bailey - Chief Engineer} c. to NW.{N. Walker - Patents} Rm{William Robotham - Chief Engineer}/Swd13/JH.14.12.38. Oil Filters. Since issuing our instructions for a depot sheet regarding the fitting of 'General' filters(Rm{William Robotham - Chief Engineer}/Swd1.13/R.{Sir Henry Royce} 8.12.38.) it has been decided to drain the oil at 10,000 miles and not 20,000 as stated. This compares with the present draining period of 5,000 where no filter is employed. The above also applies to the Wraith III instructions otherwise, as stated, the element is renewed after 5,000 miles and then every subsequent 10,000 miles. The costs given on our memo. Rm{William Robotham - Chief Engineer}/Swd1.13/R.{Sir Henry Royce} 8.12.38. which was based on draining at 20,000 miles are incorrect. Rm{William Robotham - Chief Engineer}/Swd1. | ||