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).
The performance of various Extreme Pressure (E.P.) lubricating oils and their effects on engine components.
| Identifier | ExFiles\Box 27\3\ Scan243 | |
| Date | 7th October 1939 | |
| -2- 7th. October, 1939. C.C.Wakefield submitted some D.T.D.109 which they stated was E.P. treated as a competitor to Robertson's dope but it was no good and did not do the job. The gear was wrecked. Speedolene + however, another treated oil brought out in competition by the Silvertown people was found to be satisfactory. It is believed that they use the same dope as Robertson's. The gear up to the present has been the only unit which seems to be able to take advantage of the extreme pressure lubricating qualities of an oil. When trouble was experienced with the gear on the Schneider Trophy engine it was found that Castrol oil overcame the trouble. Very recently, the Peregrine gear, which at normal outputs gave no trouble, showed signs of "plucking" badly when the power was raised to 900 take off. The gear was perfectly alright when run with Speedolene + oil. In the automobile world, the E.P. characteristics of certain oils have long been appreciated, and advantage taken of their merits to produce a lighter chassis. Dealing with the smallest increase in film strength first, we ourselves have found that oil that has been used and thoroughly cleaned by a centrifugal or bye pass filter has better E.P. characteristics than the same oil when new. This was demonstrated with Castrol XL. When new engines were run in on fresh oil, piston scuffing took place. When oil that had been run and cleaned was used the trouble ceased to exist. Another expedient that is used to run in engines, is to mix 10% of lard oil with pure mineral oil. This mixture is removed from the engine before it is assembled in the chassis. Besides piston scuffing, tappet scuffing is frequently overcome by such treatment. These are about the only two features of the power plant that at present benefit from increased film strength. The transmission of the modern automobile, however, would be in a bad way without E.P. lubricants. | ||