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 from the Vacuum Oil Company concerning winter grades of engine lubricating oil.
| Identifier | ExFiles\Box 145\1\ scan0117 | |
| Date | 7th December 1934 | |
| BY APPOINTMENT VACUUM OIL COMPANY LIMITED GARGOYLE REG'D TRADE MARK TELEPHONE WHITEHALL 1010 (14 LINES) TELEGRAMS VACUUM · PHONE · LONDON CAXTON HOUSE · WESTMINSTER LONDON · S·W·1 REFERENCE ED{J. L. Edwards}/AUTO. 7th December, 1934. Messrs. Rolls-Royce Ltd., D e r b y. For the attention of Mr. W. A.{Mr Adams} Robotham. Dear Sirs, We understand that Mr. J.{Mr Johnson W.M.} Russell Sharp discussed with you the question of Winter grades of engine lubricating oil when he visited your Works on the 29th ultimo. It has been suggested that we give you further information on this point. The grade of Mobiloil which we would recommend for such purposes in Rolls-Royce and Bentley engines is Mobiloil AF, which is of lower viscosity than Mobiloil D, which you recommend for normal use in these units. We are attaching a table showing some of the physical characteristics of these two grades, which indicate the difference in viscosity. We are also enclosing a copy of our booklet, "Evidence", and would ask you to refer to Pages 28-30, on which are described some tests carried out at the National Physical Laboratory. The curves shown on Page 30 indicate the reduced starting effort required by the Winter grade oil under the particular conditions in which the tests were made. We have not available any reliable figures for relative rates of oil consumption of these two oils, and we feel that in any case such figures would need very careful interpretation. You are probably aware that a number of modern motor car engines employ Mobiloil AF for normal work, including hot weather, and some of these are units of quite high power output. Such engines employ lighter grades, such as Mobiloil A, during cold weather. Wherever the engine is in good mechanical condition and has not undue piston and piston ring clearances, we should (Contd.) UNLESS STATED OTHERWISE ALL OILS ARE QUOTED AND INVOICED PER UNIT GALLON OF 9 LBS AND ALL QUOTATIONS ARE WITHOUT ENGAGEMENT | ||