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).
Technical memorandum discussing oil pressures and the comparison between Castrol XL and Castrol XXL oils.
| Identifier | ExFiles\Box 146\2\ scan0174 | |
| Date | 9th April 1937 | |
| 1245 W/P. To Sr. from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}10/AP.9.4.37 B.8.GA. OIL PRESURE. In reply to your memos Sr/CPN.2/7.4.37 and Sr/VA.5/ET.22.3.37 regarding the running of the above car on Castrol XXL. in place of the normal XL. we shall be interested to know how the oil pressures compare after driving at high speeds over long distances. You will see by the comparative viscosities that you will probably run into difficulties if any cold weather is encountered both in regard to starting and also danger of overloading the oil gauge; there should however, be a noticeable increase in pressures at high temperature. The danger of bursting the gauge with XXL. oil is much more pronounced now that we have the large pump. 0°C 100°C. 150°C. 16000 69 39 Castrol XL. 32000 100 46 " XXL. We have taken pressures on several units equipped with the large pump, modified grooves and two holes in the journals and the results are as follows, running at 4000 RPM. 30 lbs/sq.in. at 100°C. 27 lbs/sq.in. at 110°C 25 lbs/sq. in at 120°C. and 22 lbs/sq.in. at 130°C. It would be useful to us to know how your pressures compare with these and if you can get a transmitting thermometer fitted in the oil feed pipe from the pump to the crank-case these can be checked over. It is of especial interest to know what maximum temperature you reach after high speed driving over the long stretches that you describe. Following your comparison of the two oils we would rather you stick to Castrol XL. so that you would be representative of customers conditions and if you run into any trouble with pressures of 17 lbs/sq.in. under hot conditions. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||