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).
Cold test results for various oils showing the temperature at which they refuse to pour.
| Identifier | ExFiles\Box 145\1\ scan0070 | |
| Date | 20th December 1933 guessed | |
| Cold Tests. Temperature at which oil just refuses to pour. Mobiloil "D" - - Minus 11°C. Motorine "C" - - Minus 11°C. Castrol XL - - Minus 10°C. Castrol XXL - - Minus 15°C. Aeroshell - - Minus 27°C. H1. HE | ||