Squirrelnut: My VarmintMobile (1996 Dodge diesel Cummins with 5 speed manual transmission and 125,000 total miles now) gets its oil and filter changed (with top quality oil/filter!) every 5,000 miles.
I am the original owner and (knock on wood!) I have not had one hint of a problem with it to date.
Hold into the wind
VarmintGuy