Before I pulled out the wrenches, I'd put 3-4 ounces of Seafoam, Startron, or Amsoil Motor Flush in that puppy, go for a nice 100 mile ride and then change the oil and filter.
I did the above before switching to Amsoil in my '85, and my Rotella T6 synthetic with about 3,000 miles on it went from clear before the ride to pitch black and noticeably thicker when I drained it after the ride.
I did the above before switching to Amsoil in my '85, and my Rotella T6 synthetic with about 3,000 miles on it went from clear before the ride to pitch black and noticeably thicker when I drained it after the ride.