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).
Test method for various grades of Mobiloil, including road running and cold starting performance.
| Identifier | ExFiles\Box 145\1\ scan0127 | |
| Date | 29th June 1933 guessed | |
| For (b) a G.E.C. instrument was used, which was also checked against the substandard. It read 1½% low on that part of the scale used during the tests. For (d) a Hasler tachometer was used, which was calibrated and integrated the revolutions over a period of three seconds. 5. Oils tested. The oils used were guaranteed by the Vacuum Oil Company to be standard samples of the grades known as Mobiloil A, AF, BB, and D.{John DeLooze - Company Secretary} No independent test was made of these oils, but a list of their characteristics, as measured and supplied by the Vacuum Oil Company, is given in Table 111. 6. Test Method. The procedure agreed upon, adopted and observed in each case, was as follows:- The oil already in the sump was drained out. One gallon of the oil to be tested was then placed in the sump, after which the engine was run for thirty minutes. This oil also was drained off, the engine then being regarded as uncontaminated by any previous oil. Next the correct quantity, viz. eleven pints, of the oil to be tested was put in the sump, a sample being taken by the observer. The engine was then started up, and after running idle for a few minutes the car was driven 50 miles, about ten of which were through traffic and 40 on the open road. The official observer accompanied the driver, and the log of these journeys is given in Table 1. On returning from this run, the carburettor and radiator were drained, and the car was pushed into a chamber artificially cooled, where it was left all night. The following morning the battery was removed from the car, and another battery (which had also been kept in the cold room and whose condition of charge was known) was substituted. The 600 ampere shunt, the ammeter and the voltmeters were properly connected up. The engine compression was not changed nor the sparking plugs removed. The ignition switch being off and the clutch out, the starting switch was next closed and readings taken of voltages, currents and speeds of the starter motor, and of sump oil temperatures. A second similar test was then immediately taken with the clutch in and the gear in neutral. The time taken for each set of readings was about 5 seconds. In such a short time the sump oil could not have been much disturbed, so that the sump oil temperature gives a reasonable indication of the general engine temperature. The results of these tests are given in the first eleven columns of Table 11. In the last column the corresponding starting torques at the motor shaft are given. The method of arriving at these will be found in Section 7. For the tests on Mobiloil A, AF and BB, one battery was used. A first test (June 2nd) upon Mobiloil D shewed certain discrepancies, which led the observer to suspect that this battery was beginning to shew signs of fatigue. The series on Mobiloil D was therefore repeated on the same date with a fresh battery, and the figures in the table are those of the repeat test, which are included as being more reliable. | ||