Don wrote:
5. I'm running straight 50 weight "racing" oil, which brought the pressure
up a few notches, but not enough to be "normal".
With a straight grade oil, the viscosity change over the temperature range
will be much greater than a multigrade. Your 75 psi when cold is a function of
the 50 weight. If you ran Castrol 20W50, your cold pressure might only be 65
but your hot readings would be virtually the same. If you did no work to your
oil pump, some of the variation with temperature may be due to the worn state of
the pump. This wear will make less difference at cold temperatures, pumping cold
oil than at operating temperatures where the increased tolerances in the pump
will reduce the efficiency pumping thinner oil.
regards, John
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