Hi Glen:
You may have missed my earlier post regarding synthetics. If there is a
concern with an old engine it may take an oil change to clean it up - if it
is not so worn as to prevent this. Obviously if the engine/carburetion etc
are so worn out as to simply contribute to poor running, synthetics are a
waste of money.
The benefits of synthetics are simply that they allow an engine to start
easier from cold and they deliver lubrication immediately after start up.
There is no waiting for thick cold oil to make its way to the friction
surfaces. Additionally, synthetics can safely operate at much higher heat
and pressure levels without breaking down and thickening. They maintain
their viscosity. Finally, they are able to work safely for much longer
periods because of this ability to withstand breakdown and will resist
compounding with combustion products to create chemical adversaries within
the engine.
Many viscosities of synthetic are now available. I am using 15-50 in my
MGB with excellent results. I also use it in my Chevy van which does heavy
pulling. There are is an amazing variety of brands and viscosities out
there. You should easily be able to choose one to suit your recommended
oil pressure requirements.
With that in mind, note that synthetics don't necessarily require the same
high pressures as conventional oils to do their work. Keep in mind that
the high pressure is designed to do two things: they keep the oil moving
and cooling the engine, and they ensure adequate supply - especially under
heavy load, low rpm, and at start up. Synthetics do these jobs more easily
than conventional oils because they are made of uniform molecules and
because they are much more slippery. They get there faster, can withstand
much more heat without breakdown, can carry greater loads because of the
uniform molecular size, and are adverse to the formation of by products.
Lastly, note that synthetic automobile engine oil and other related oils
are not new. They've been around for about 25 years now. Aircraft have
been using synthetics for over 50 years. I should think that a half
century of development should have made them superior to "the old standbys".
John
>> -----Original Message-----
>> From: John McEwen
>> Sent: Saturday, November 24, 2001 10:56 PM
>> To: DEVierling@aol.com
>> Cc: british-cars@autox.team.net
>> Subject: Re: synthetic oil?
>>
>> Further to the use of synthetics vs conventional oils, the drain interval
>> on synthetics is vastly extended because they don't form the nasty
>> byproducts during their interaction with the products of
>> combustion because synthetics don't have a petroleum base. The drain
>interval is
>> extended for normal service to between 25 and 30,000 km.
>
>Assuming John is right, there probably would be an advantage to running and
>storing a car with a synthetic.
>
>However (A), an old engine WILL release old gunk into the new synthetic oil
>as the new wonder product works its magic.
>
>However (B), viscosity remains important and you shouldn't use a viscosity
>that is way below what the engine was designed for. Todays engines are
>built to much closer tolerances than MG was able to produce. My Rover V8
>engines show a drop in oil pressure when I drop just one viscosity step.
>
>Glen
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