>when I first turn on the motor, it runs the oil pressure at about 50 lbs.
>Once it's fully warmed up and I've been driving it around, the pressure
>drops to about 35 lbs of pressure. (The oil according to the dip stick is
>at a good level.)
>Is this normal for engines? And if not, is this symptomatic of anything
>I could possible check out (failing oil oil pump or whatever)?
Yup - normal, for a slightly worn engine.
When you start an engine - any engine - cold, the bearing surfaces,
bushings, etc are cold, and the metal surrounding them is relaxed. The
clearances are closer than at any other time (which is why most good shop
books insist on you checking clearances when warm). As the engine reaches
normal operating temperature, the metal around the bearing surfaces expands
to their normal working clearances. This allows more oil to get through, and
therefore lower oil pressure.
Nothing to worry about, providing the clearances are not excessive. If
you're concerned, drop the sump and check the main bearings. The wear
indicators on the mains will show how much is gone.
PS - This is the reason that most british cars adopted the 'idiot light'
rather than an oil pressure guage. Owners were worried that the pressure was
too low - Same for the mid 60's temp guages, later ones always read low with
the correct sender.
1954 Austin A40 Somerset
1963 Triumph Spitfire 4
1966 Triumph 2000 Sedan