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We
have met some concern about the use of synthetic oils,
in that they have been attributed to causing low engine
oil pressure when hot. We would like to clarify the
situation. To this end, we have contacted Castrol (UK)
Ltd. for their advice and this is their response:
Oil
pressure is directly related to viscosity and it is
therefore not the difference between synthetic and non-synthetic
oils that causes the difference in pressure, more the
fact that modern synthetic oils are of a lower viscosity
than the A series engine was originally designed for.
Modern,
new generation, engines are being designed to run on
lighter viscosity oils to aid lubricant flow when cold
and provide less viscous drag when hot thereby aiding
fuel economy. The lubrication system in older engines
is designed to cater for larger working clearances on
crankshaft and camshaft bearing journals, valve gear
and other moving parts, plus oil galleries will be larger
and the oil pump will be of a suitable design to pump
oils of a heavier viscosity irrespective of their base
oil type.
Synthetic
oils are designed to give greater film strength and
higher levels of lubricity together with increased thermal
stability and better resistance to oxidation. They are
also able to maintain their properties when used under
arduous or extreme conditions. These special properties
also enable lighter viscosity, energy efficient oils
to be used whilst offering an enhanced level of protection
and performance.
Whilst
the lower viscosity of some synthetic oils may lead
to reduced oil pressure, it does not necessarily mean
reduced protection. However, owners who are nervous
of a reduction in pressure should consider using Castrol
Formula RS 10W-60 which will give rapid circulation
when cold but will retain a substantial viscosity when
up to its full working temperature.
We
would like to thank Castrol (UK) Ltd. for their kind
assistance.
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