A return to the thread I noticed some time ago, but it did not clear the air
for me!
I use my '67B year round, unless there is salt on the roads, and change 20W50
oil and filter, as recommended at 3K intervals. ( about twice per year).
Oil pressure never drops below 40psi on tickover, or rises over 60psi at
3-5Krpm.
In Summer the needle stays within this range proportional to the revs as soon
as she fires up.
In Winter, at frosty temperatures by the time the temperature gauge reads
normal, I can see up to 50psi running pressure, but rarely any higher. I have
discovered that everything reverts to normal if I later hit a halt sign and
sit at tickover for a few moments, if I do not need to stop it can take a
further 5 miles for normal 60psi to be indicated.
I have rationalised this by guessing that the column of very cold oil in the
capillary initially suffers from some 'boundary' effects which inhibits the
transfer of pressure from the warm oil below to the gauge, dropping the revs
for a moment gives it a chance to warm up & perhaps drain back?
But this capillary theory does not seem to fit with the Physics I learned at
school?
TIA
Colin
'67B
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