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 oil change intervals, issues with Ethyl gasoline, experiences with benzol fuel mixtures, and spark plug compatibility.
| Identifier | ExFiles\Box 88\1\ scan0211 | |
| Date | 15th November 1935 | |
| -2- Bentley Motors (1931) Ltd. November 15, 1935. As a matter of fact, is it not correct that, within reasonable limits, equally good lubrication is obtained from a relatively thinner oil, the only objection to its use being a larger consumption? [Handwritten] Possibly I am being too particular as to the exact viscosity to use - [/Handwritten] I appreciate your comments concerning the other matters referred to in my letter of August 28. In that letter I referred to the recommendation in your instruction book for changing engine oil every 5,000 miles, as it was so at variance with my former practice and recommendation in the instruction book of my P-II. I have always made it a practice to change oil at least every 1,000 miles, and in inquiring regarding the absence of an oil filter, I had in mind that it might be better to change even more frequently than this. Your further comments in this respect will be appreciated. Your letter of September 11 refers to the use of Ethyl gasoline. It has been my observation here that it frequently happens that cars that have used this type of fuel have trouble with sticking valves, especially if the cars stand idle for a few weeks. I know of several cars, including some P-II's, where the valves have become so badly stuck that they could not be removed even with a hammer. Also, on cars which I have had, and others that I have observed, which have been run on Ethyl gasoline, a very rapid corosion of the exhaust system, particularly the silencer, has been experienced. I have no proof that these troubles come from thelead in the Ethyl gas, but circumstantial evidence seems to point that way. On my P-II, in which I very rarely used Ethyl, I had no trouble either withthe valves or the exhaust system over a period in which the car was run about 40,000 miles. 201.TA In the case of the P-II, the use a an anti-knock gasoline was not as necessary as with the Bentley with its higher compression. In trying out various fuels here, I have found that a gasoline put out by the American Oil Company, under the trade name of Amoco, and which contains a certain percentage of benzol gives by far the most satisfactory operation. Even when using Ethyl gasoline I find some tendency in the Bentley motor to detonate, though not badly. With the gasoline benzol fuel there is absolutely no such tendency, and the running of the motor is hence more pleasant. Power and consumption are also slightly better. Have you had any experience with benzol mixtures? In this case again I would like to know if there are any objections to using it. To date I have not been able to find out just what percentage of benzol is in the mixture, but will do so, as there is probably a maximum percentage that is desirable. I believe benzol is considerably hotter in combustion than gasoline, and I know in the early days it, on this account, caused damage to valves. I am so very pleased with the Bentley, and anxious to give it the very best of care, that I am taking the liberty of writing to you at such length, as we have no information in this country on the subject. Another matter that I am trying to work out with Mr. Adkins, Service Manager for the Springfield Manufacturing Company is a suitable spark plug manufactured in this country. Apparently the 14 mm. plugs manufactured here employ a slightly different thread, although of the same pitch, from that for which the [Handwritten in left margin] at no lead | ||