HOLA el grande diesel hombres;
Ive been noticing lately my idle oil pressure when hot after 30 minutes @ highway speeds has gone from about 1.3 bar to 1 bar. Over a period of about 3-4 months. The last months @ winter temps of course.
My sled is a 83 300sd w/ 230k
Pressure is 3 bar @ startup in morning and pegs @ anything over 1300 rpm and immediately upon acceleration.

Last oil change was 1500 mi ago. My son did it and used (ugh!) regular exxon 10/40.
Im sure my valve guide seals may be going. Slight leak from oil filter housing and from oil dipstick tube @ block. What would you suggest to get the pressure up?
What oil should I put in (Im going to change it out) to go in hottest weather? Should I up the weight? Will going full syn help?

I absolutely LOVE this car, at present slightly more than my son, and want the best fix.