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 C.C. Wakefield & Co. Limited discussing the comparative properties of paraffin and asphaltic base oils.
| Identifier | ExFiles\Box 32\3\ Scan052 | |
| Date | 16th November 1920 | |
| RESEARCH DEPARTMENT. X1583 C. C. Wakefield & Co, Limited. MANUFACTURERS of HIGH CLASS LUBRICANTS. GOVERNING DIRECTOR, SIR CHARLES WAKEFIELD, BART. MANAGING DIRECTOR, W.R.GRAHAM. LABORATORY: Wakefield House, 30&32, Cheapside, London E.C.2. 16th November 1920. F.{Mr Friese} Metcalfe Fisher, Esq., Dear Sir, In the past it has generally been conceded that paraffin base oils are superior lubricants to asphalt base oils, because the temperature coefficient of viscosity is lower in the case of the former class of oil than in the latter. Or, to put it another way - the drop in viscosity per unit temperature rise is less in the paraffin than in the asphaltic oil. That means that if a moving part operates throughout a range of temperature the friction loss due to the oil must be of some moment at the limits of the range when using an asphaltic oil; on the other hand, a much smaller variation from the optimum is perceptible with a paraffin base oil. In a circulating system when the oil is subjected to elevated temperatures in contact with air asphaltic oils are more prone to produce solid decomposition products than are paraffin oils. This propensity combined with the greater volatility of the asphaltic oils means more "carbon" because the solid matter is ever increasing normally in the oil, and is being concentrated by the loss on evaporation, and the burning in the cylinder. The Western Oils, or the asphaltic oils, have received comparatively little attention in this country until recently, and have therefore not reached the same degree of perfection as have the Pennsylvanian, or paraffin, oils. Active researches are being conducted by us to improve them, but at the moment their application is limited, when efficiency is demanded, to specific cases where the above considerations do not apply. We are doubtful whether the belief that Price's oils have been derived from asphaltic base oils for the past 50 years is correct. | ||