The Instruction Book advises Wakefield's Castrol 'AA' or Mobiloil 'A' for the gearbox and 'XL' for the engine. Castrol Classic Oils Technical Dept. advised me that the modern equivalent for both is Castrol XL30. Considering that Alvis would not have specified different oils without a reason I asked Castrol whether 'AA' was a 'heavier' or 'lighter' oil than 'XL'. They couldn't answer that but assured me that XL30 would be suitable for gearbox and XL 20-50 for the engine. Uneasy with that answer, investigation of the web produced an image, from an Australian trader, of a prewar, 1 pint, glass, Castrol oil bottle with a steel screw-on conical painted funnel with the words: "Castrol Motor Oil" and below: "AA" and below that, "SAE 40". That suggests that the Alvis advice, prewar, was for the gearbox to use SAE 40 and the engine SAE 30. Replacing the gearbox with Millers 40, from Castrol 20/50 and after three trips in London traffic I found an improvement in engaging 1st gear, marginal (perhaps imagined) improvement in gear changing and the gearbox is quieter. Posted by jamie mill 19/01/2013 15:15:57
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