On 27/07/2020 12:21, newshound wrote:
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 ,
Â*Â*Â*Â* 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.

The soot was as much as anything oil exposed to high temperature blowby
gases.

The fact of the matter is that materials have come on hugely. A 1960s
BMC A or B engine needed new big end shells at 30,000 and mains at
60,000 or a complete rebuild with rebore and new pistons at 90,000.

Most modern engines are 120-180k before there is *any* noticeable wear.

Metals are harder, oils are better and machining is to far tighter
tolerances.

--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal