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).
The use of specific viscosity oils for 'M' series Bentley cars and Phantom III gearboxes.
| Identifier | ExFiles\Box 145\3\ scan0183 | |
| Date | 24th May 1938 | |
| 8 1235 To LA.{L. A. Archer} from Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} c. Hd.{Mr Hayward/Mr Huddy} c. Br.{T. E. Bellringer - Repair Manager} W/N. c. Pk. W/K.{Mr Kilner} Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls}5/MH.{M. Huckerby}24.5.38. CHASSIS LUBRICANTS. On 'M' series Bentley cars we are going to use a viscosity 30 oil for the engine and gearbox. The oils conforming to this are known now as Price's M, Castrol XL, Vacuum A, Shell Double and Duckham's NPXX. All these companies have agreed to label their oil containers from now on with the viscosity number. Castrol XL, underlined, is a 30 oil but the old XL was of 50 viscosity. P.III gearboxes should not be run on XL but on XXL when a Castrol oil is used. We are not proposing to tell customers to use Castrol XXL in old cars if and until we have had several complaints of excessive oil consumption using XL.30. Rm{William Robotham - Chief Engineer}/Gry.{Shadwell Grylls} | ||