On 26/07/2020 14:45, Jethro_uk wrote:
On Sun, 26 Jul 2020 09:31:11 +0100, newshound wrote:

On 25/07/2020 18:53, Dave Plowman (News) wrote:
In article ,
Max Demian wrote:
Worked on the pumps one summer in the mid 60's, often got asked to
check the oil and top it up. We were required to refill empty oil
cans from the bulk tank in the workshop, and try to make sure the
customer didn't see that we didn't have to remove an aluminium tab
from them. Castrolite and XL in those days.

Probably filtered sump oil.

You'd need some filtration to make used oil look clean again. Although
it can be done in a factory. Many small garages used old sump oil to
heat the workshop in the winter.

Exactly, no chance of that in a workshop of those days.

I still find it mildly astonishing that you can still see through the
oil in my Jazz after a year.

Well the darkening is (mainly) soot from the combustion bypassing the
rings, so I am guessing they've improved the tolerances ?

More likely I think improvements in combustion technology from a
combination of injection, sensors, and ECUs, leading to much less soot.