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).
Engine test examining crankpin deposits and overall condition after a prolonged mileage run using Aero Shell oil.
| Identifier | ExFiles\Box 179b\3\ img343 | |
| Date | 16th March 1933 | |
| -2- passage, whilst at the same time centrifugal action is reduced; in this way, they said, a state of equilibrium is attained and barring an access of foreign matter, such as pulverised bearing metal, it is very unlikely that the oil flow would become obstructed in a period of time that could be run before general maintenance routine called for a complete overhaul. In order to test out this theory it was agreed to run the same engine a further large mileage without removing the deposit from Nos.1, 3, 4 & 6 crankpins whilst Nos. 5 & 2 were cleaned out. (3) After completing a further 23,700 miles this engine was dismantled sufficiently to allow the main and big end bearings, and the crankpins to be examined. The examination rather confirmed the theory put forward by Shell Mex with regard to crankpin bore deposit. Nos. 1, 3, 4 & 6 crankpins had not appreciably increased the amount of deposit, approximately half filling the crankpin bore. Nos. 2 & 5 crankpins contained about the same amount of deposit, but it appeared slightly less dense than the others. This test rather shows that there is no danger of the crankpins being filled with deposit sufficiently to block off the oil flow, even after a large mileage. The remaining parts of the engine that were examined were in very good condition. All the bearings, (main and big end), were very good indeed, the crankpins and journals were also in equally good condition. The bottom half of the crankcase was entirely free from sludge (definitely better than when using our standard oils under similar conditions). The under sides of the pistons were exceptionally clean and free from deposit. The cylinder head was not removed, the previous test having shown that the oil is satisfactory as regards carbon deposits. An analysis of the oil taken from the sump at the conclusion of the test did not reveal any harmful constituents. As the result of these prolonged tests we can see no reason to expect any deleterious effects as the result of using Aero Shell oil in our car engines. | ||