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).
Piston scuffing trouble in relation to standardizing different grades of S.A.E. oil.
| Identifier | ExFiles\Box 145\3\ scan0169 | |
| Date | 8th April 1938 | |
| 1235. By.{R.W. Bailey - Chief Engineer} from Rm.{William Robotham - Chief Engineer} c. Ms. c. HRC. c. Da.{Bernard Day - Chassis Design} c. Mx.{John H Maddocks - Chief Proving Officer} c. Da{Bernard Day - Chassis Design}/Jnr.{Charles L. Jenner} c. Ha/GWA. Rm{William Robotham - Chief Engineer}3/R.8.4.38. We were just about to standardise S.A.E.20 oils when we ran into piston scuffing trouble. Up to this date we had run several hundred thousand miles on this oil, and we had never been able to detect any undesirable results, except a tendency to increase oil consumption. It will be noted that on the last 15,000 mile Bentley with the overdrive, the oil consumption was consistently over 2,000 miles to the gallon using 'Mobil A' oil, which is an S.A.E.30 - one grade thicker than S.A.E.20. The attached report shows that piston scuffing is not, as we originally thought, due to the use of thin oil. Piston plating should pay for itself by cutting down the necessary amount of running in. The main advantage which we hope to gain from this oil is the reduction of cylinder bore wear. Certain customers cars are being kept under observation by GWA., with a view to establishing the value of light oils. Rm.{William Robotham - Chief Engineer} | ||