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 Price's Patent Candle Company comparing the properties of motor oils, including viscosity, flash point, and composition.
| Identifier | ExFiles\Box 144\1\ scan0005 | |
| Date | 8th April 1910 guessed | |
| Price's Patent Candle Company Limited No .......................... 2. Messrs Rolls-Royce Limited, Derby. Cont'd.{John DeLooze - Company Secretary} 2nd That the viscosity of the oil at working temperature should be as high as possible to prevent metallic contact and friction. If we apply this criterion to the oils before us we should give the palm to Motorine B which, with an initial viscosity of, say, 8000 @ 60° gives an ultimate viscosity of 90 @ 212, or say 1.5%. If we apply the same rule to your new samples we find for No 1, 703 @ 60 against 42 @ 212°F or say 6%; in the case of No 2, 983 @ 60 against 48 @ 212°F, or say 5%. In each case the ratio is higher in the case of your oils but you will observe that while the ratio is higher the actual viscosity is only about half of that of Motorine B at the same temperature. FLASH POINT, in both of your oils, is satisfactory although, in both cases, it is a long way below that of Motorine. This is probably due to the higher percentage of volatile matter which is shown by the great loss dealt with in the next paragraph. EVAPORATION. The endurance of any oil must to a large extent depend upon the rate at which it evaporates under working conditions and this in turn is regulated by the percentage present of material which may be volatilized at that temperature. You will observe that under equal conditions, 1 hour @ 370 F, your oils lose on an average 8% each as against a loss, in the case of Motorine B of say 0.6%. COMPOSITION. Both of the recent samples which you have submitted to us are pure hydrocarbons. As we have so long been advocates of compound oils in preference to pure hydrocarbons we do not like to urge our own opinion upon this much debated question as final in considering the value of any oil. We may, however, subject to that qualifying clause, say that we should expect Motorine B, when all the particulars before us and before you have been considered, to give better lubrication and to last longer than the thinner pure hydrocarbon oils with which this present letter is concerned. We enclose a copy of a paper upon "Fuels and Lubricants for Internal Combustion Engines" which we have reprinted from the Motor Trader in case it should interest you. Yours truly, PRICE'S PATENT CANDLE COMPANY LIMITED. [Signature: Haldane Wilson] | ||