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 from Shell-Mex and B.P. Limited discussing oil specifications and the marking of oil grades for gearboxes.
| Identifier | ExFiles\Box 145\3\ scan0282 | |
| Date | 5th April 1938 | |
| CONTINUATION SHEET No. 1. FROM SHELL-MEX AND B.P. LIMITED TO Rolls-Royce Ltd. DATE 5.4.38 rating for engine oils and also the S.A.E. rating for gear oils, which you will appreciate are quite different and we therefore rather feel that reference to a marking of this type for the lubrication of gear boxes, may cause confusion. The figures for Golden Shell (Extra Heavy) are right on the top limit of an S.A.E. 50 engine oil and we think that this would probably suit your purpose better that would Triple Shell (Heavy), comparable specifications being as follows:- TRIPLE SHELL GOLDEN SHELL (HEAVY) (EXTRA HEAVY) Spec. Gravity @ 60ºF .885 .892 Closed Flash 445 500 Visc. Red.1 @ 70ºF 2310 3420 " " @ 140ºF 260 350 " " @ 200ºF 85 106 Pour Point Below 0ºF Below 0ºF So far as Golden Shell (Extra Heavy) is concerned, we would not be prepared to mark packages of this as "50" for the reasons mentioned above, though should you decide that Triple Shell (Heavy) would be quite satisfactory for your purpose, so far as the gear boxes are concerned, then we would certainly make arrangements for packages of this grade to be marked "50". We do not know what views other oil companies express on this point but our own views are that in the case of the gear box, it would be preferable from your point of view not to refer to viscosity ratings but rather to specific grades, as done formerly, particularly as such recommendations to specific grades can be linked up with the recommendations given by you for other parts of the chassis, etc. In connection with the latter, we thank you for agreeing to incorporate the equivalent grades, so far as we are concerned, to those already shown in the instruction book, though in connection with the rear axle, we quite | ||