Originally Posted By: Doug Hillary
The 20w-50 viscosity lubricant was especially developed during 1958-9 by Duckhams for use in the BMC (Austin - Morris) Mini. It was released about the same time as the car
This lubricant was needed because of the integrated engine-gearbox in these cars - they shared the oil with a common sump. Castrol followed with a 20w-50 during 1960
Believe me, they needed a 20w-50 lubricant - but it was really all about a very poor design concept and marketing gone wrong!!
The "A" Series engine in these cars always ran very well on a 20w-20 or 20w-30 lubricant in other applications
During the 1960s the 20w-50 viscosity quickly became the "fix-it"viscosity for poor design, leaky engines and etc. Of course it had other applications.
In Europe at this time 10w-30 had a great following and for example the VW Beetle ran very well on 20w-20 lubricants - Owners were swayed by Advertising and ran the new 20w-50
It has some applications but probably the real need is few and far between
Yes. I lifted it from
this thread, which was the first that came up in my search.