I will throw in my $.02 on this! There are two properties of oil that one
must consider. The first is viscosity - how 'thick' the oil is. The second
is viscosity index - how rapidly the viscosity changes with temperature.
Multigrade oils have a much flatter viscosity index than single-weights.
So - both of the ideas expressed below are pretty nearly right!
Len Bugel
'51 TD
'57 MGA
On Thu, 29 May 1997, Paul Hunt wrote:
> pbailey wrote:
> >
> > Doesn't 20W50 mean when its cold it will be 20W to help cranking and
> > when it's hot it will be 50W or somewhere in between or do I have this
> > backwards?....Pat
>
> I seem to remember reading that before multigrades were introduced it
> was common to use a different grade of oil in winter (20W) to summer
> (50). The 20W/50 means that it performs as a 20W would in winter and 50
> in summer.
>
> PaulH.
>
>
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