fuel type

[TONY!]

I would follow what the manufacturer recommends.
There must be a sticker somewhere on the car, check the glove box.
I would also think that the manual would tell you what you should feed it too.

If I were to guess, I would say that you could use the regular unleaded.
If you hear pinging, go to a higher octane gas.

If you have an '86, then your compression ratio is 9.2:1
That does not sound so high to me.
High compression ratio engines and forced induction engines (supercharged/turbocharged) will need higher octane fuel so they don't ping.

Unless you have a lot of carbon build up (which would increase your actual compression ratio), I would bet that the regular is good enough for you.