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 discussing three different oil samples to compare the effectiveness of a general filter versus no filter.
| Identifier | ExFiles\Box 136\3\ scan0108 | |
| Date | 4th December 1940 | |
| oil filters 1139 Rm.{William Robotham - Chief Engineer}11/ML. 4.12.40. T.C.Worth,Esq., Aircraft House, MARKET HARBOROUGH. Dear Tom, I am sending you, under separate cover, three test tubes of oil. One is a sample of oil which has done just over 15,000 miles and been kept clean by a general filter, the elements of which have been changed regularly. The oil consumption of the car during this run has been 2,300 m.p.g. The second sample is of the same type of oil, which has done just over 7,000 miles without any by-pass filter. The oil consumption over this period was 1400 m.p.g. The third sample shows the effect of fitting a by-pass filter to the power unit containing dirty oil. The way in which the filter has cleaned the oil is rather instructive. The actual mileage in each case in question is written on the label of the test tube. Yours sincerely, | ||