Up until the very early 1960s, fairly basic oils, generally SAE30 oils, were used in car engines. Towards the end of the 1950s a major development took place in Britain which forced oil companies to rethink vehicle oil. Britain was at the forefront of this development and ahead of the USA at the time. The major late 1950s development was, of course, the introduction of the Mini and the problems presented by having the engine and gearbox sharing the same oil, something only seen previously in motorbikes. Initially, oils such as Castrolite 10w-30 were recommended for the Mini but the use of these thin oils often led to piston scuffing and gearbox problems. The solution was the introduction of a heavier 20w-50 multigrade oil. Many years later the recommendation was changed to 10w-40, to help with fuel economy, but the result was a host of gearbox warranty claims.
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