Conventional vs Synthetic

["Jon Durham" <Jon_Durham@domain.elided>]

Some time ago I received this information on conventional vs synthetic
oils. I'd like to know other's opinions.

#1) The viscosity of synthetic oil can be adjusted to be less
temperature
> dependent than a conventional oil. So, a synthetic oil might be less
> viscous when cold than conventional oil, and still more viscous hot
than
> conventional oil. For extreme climates ( extreme here means alaska or
> siberia) there are starting advantages to the synthetic oil. For more
> temperate climates, there is perhaps a little fuel efficiency during
> warm-up in favor of the synthetic - but inflating the tires is likely
as
> big an advantage.
>
> #2) The synthetics fractionate at much high temperatures - so if you
> regularly heat the oil to 400 or 500 degrees, the synthetic breaks
down
> less over time, producing less heavy tar deposits in the engine, and
> providing better lubrication over long time intervals. Pretty much the
> only situations with passenger car engines which run this hot are cars
> running very low on oil, and turbocharged cars which use the oil to
cool
> the turbine bearings. In this case, a useage pattern of running the
engine
> ( and turbine) very hot, then shutting off the engine ( and cooling
oil
> flow) just cooks the oil in the turbine bearings, eventually coking up
and
> blocking the oil flow in the bearing. Here, the synthetic lubricants
do
> help last longer - but it is still smarter to let the turbine cool
down

Jon A Durham
256-722-8692
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