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).
Letter discussing various theories on engine wear and the effectiveness of an extra oil system to prevent cold-knocking.
| Identifier | ExFiles\Box 16\1\ Scan099 | |
| Date | 7th October 1925 | |
| ROLLS-ROYCE OF AMERICA, INC. SPRINGFIELD, MASS. 4740 Oy3-E-10725 October 7th, 1925. Mr. E.{Mr Elliott - Chief Engineer} W. Hives, Rolls-Royce, Ltd., Derby, England. Dear Mr. Hives: Re Extra Oil Just now the industry is all heated up about engine wear - its cause and cure. Some believe it is condensation water in the oil mixing with sulphur in the fuel causing corrosion. Others that it is dilution. This is strongly denied by another group which says a certain amount of dilution is beneficial. Others put it all down to dirt. These divide into two groups, the air-cleaner enthusiasts, and the oil-filterers. We have proved that for passenger cars in parts of the country where hard roads are the rule, the cause of cylinder wear and the cause of "cold-knocking", are the same. Namely, that all the oil is washed off the cylinder walls by fuel, every time the engine is started cold. Since operating the extra oil with the pilot jet, experience on 102 CX{Major Len W. Cox - Advertising Manager} which has run 23,500 miles, shows that there is no cold knocking and the condition of the cylinder bore and pistons is the most perfect we have seen on any car, the bores being virtually unworn and polished like glass. None of the left hand cars has any appreciable cold knock in starting, whereas the previous cars nearly always knocked when started in cold weather. 12-MC knocks for one to four minutes when started from cold. | ||