[Vwdiesel] Low oil pressure question

[David Ratzlaff]

An '82 Jetta dsl that I have been asked to work on has over 200K on the engine, has good oil presure when cold, but when warm shows none on the aftermarket gage installed, and oil light flickers. Also has not very much at higher RPMs when warm.
Is it worth my while to try replacing the oil pump, or do I just chalk it up to a worn-out engine? Any benefit to running a single-grade oil, like 30W? (It currently has synthetic in it.)
Thanks,
David