I'll throw in my 2 cents.

Your car was made 16 yrs. ago. How widely available, widely used was any form of synthetic in 1986?

I won't argue that synthetic MIGHT be better for newer cars. It's my belief that in older cars, you're wasting your money and that you stand a good chance of creating leaks that weren't there before. Don't ask me how I know this.

Use a Mahle/Knecht, Hengst; Mann filter and a quality conventional oil - take your pick, but stick with the one you choose and change it at least every 3,000 miles and you'll be fine.

Larry Bibles "change it hot/change it often" is sound advise. You'll drain more oil and flush contaminants.