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).
Oil quality testing, sludge deposition, and disagreements between Wright and various oil companies.
| Identifier | ExFiles\Box 27\3\ Scan234 | |
| Date | 15th May 1939 guessed | |
| 27. Oil. The Wright Company has pursued the question of quality of oil very vigorously, and claims to have effected considerable improvement as a result . The Company led the way by evolving a rating chart, which gave merit figures according to the results obtained on main engine test, weighing them according to what was considered their relative importance, and deriving a rating figure fro the oil. The process of inspection is rather lengthy and laborious, and liable to wide variations in interpretation, but Wrights say that the results actually vary very little with different observers. The oil companies are inclined to disagree with the emphasis which Wrights place on certain features, for example, wear and asphaltenes in the used oil, and they have put forward an alternative Inspection Form, in collaboration with the S.A.E. This also involves an enormous number of recordings. Wrights have suffered a great deal from sludge deposition in the engine, and say that often engines would not need stripping at 500 hours were it not for the necessity of cleaning them. They have, therefore, placed emphasis on this aspect and Mr. Nutt produced a sample of used oil which had thrown down practically no sludge after having been centrifuged in the DeLaval Precision Centrifuge at 10,000 g.{Mr Griffiths - Chief Accountant / Mr Gnapp} An older type of oil had thrown down 2,400 times as much sludge. While the oil companies are doing all they can to over-come sludging, they feel that Wright's test is unfair, for as Dr. Leland of the Esso Research Laboratories said, a used oil which threw down asphaltenes in the centrifuge was probably, a good engine oil because it had held the sludge in suspension while in the engine. Both Wrights and Pratt & Whitney have tested DTD 109 oil (brand unknown). Neither of them was at all | ||