In article ,
Doctor Drivel wrote:
Oil gets contaminated in an engine. So it's not just the oil itself
but how well it is filtered etc and whether those contaminants can be
removed or not which determines its service life in practice. That's
one reason why lifetime oils for gearboxes etc have been around for a
long time - but not for engines.

The contamination breaks down the lubrication qualities of mineral oil.
"Pure" synthetics do not break down, or take an amazingly long time to
break down. Read the Popular Science article and the tests Ford did
nearly 40 years ago.

So there's no need for a filter, then?

As usual you have just visited a few websites and are quoting the bits
that suit you without any understanding of the subject.

It is clear you do not know anything about oil. About 25 years ago I did
some work in an oil research lab around Oxfordshire.

Cleaning the loos?

The Tribologists said "only ever use fully synthetic oils", as the
lubrication is vastly superior in every way. Most people thought it was
only for "sports" cars, they said "use it in all engines". One stated
that in bumper to bumper city driving the water pumps do not run fast
enough creating hot spots in the engine. This would bake mineral oil
onto surfaces. Anyone who has stripped down a BMC A series engine will
have noted the black baked on oil around the cam followers, which needs
scraping off.

You'll find black baked on deposits on an engine run exclusively on
synthetics from new too - as I discovered when changing the rocker cover
gasket on my BMW.

Oh - if you used a modern fully synthetic oil in an A Series engine,
you'll experience rapid cam and tappet wear. They don't have the correct
additives for this type of engine. Those additives aren't suitable for
cat. equipped engines, so inferior types are used.

--
*If at first you don't succeed, destroy all evidence that you tried *

Dave Plowman London SW
To e-mail, change noise into sound.