Everyone has an opinion about oil. Mine is based on about 800k of
personal driving. I have bought mostly new cars (mostly VWs) since 1963.
Used Valvoline Racing Oil until 1992 then switched to pure synthetic.
With valvoline I changed every 3000 miles, with synthetic I changed
filters every 3000 mile and changed oil every 50,000 miles. Never had an
engine problem except for the 90 Carat that I'm working on now and I'm
changing the heads because of a water leak. 176k miles, head are still
good, just wore out the seal. I could have just removed the heads,
cleaned and resealed and they would keep on going.

Steve & Jo Ann Wacker
Grand Junction, Co.
90 Carat
86 Syncro
01 Subaru Outback