I recently changed the oil in my 93 Jetta powered 84 5sp vanagon.  I
recalled someone suggesting diesel-"branded" oil so I put some of that in
this time.
  I was running 10-40 Mobil labeled SM/CF and I switched to Delo 15/40
labeled CJ-4/SM.  It has been in the high 80s to 100f here in the Eastern
Columbia River Gorge area of the Pacific Northwest.  My old oil had maybe
3000 miles in it.

  I noticed about 10 lbs/psi (+/-) increase in my oil pressure, maybe 15
when my oil temperature gets up to it's higher operating temperatures.  My
vehicle is now operating at.... interstate/highway sustained speeds...210f
Oil temperature with oil pressure of 65psi at 3700rpm (60mph)  With the
other oil, I was seeing about 55psi of oil pressure at the same oil
temperature and rpms..  At idle, with the temperature up there, both oils
give me 20psi oil pressure.

  Posting this for anyone wanting to have the numbers to check against their
own and to mention the increase in OP with the change in oils.