On your tbi? From what I can tell by searching around, it seems to be low grade. I've been running premium on mine since I got it three months ago but I'll be due for a fill up in about a week so I thought I'd see what the majority of the board runs on theirs and see if anyone has had any ill effects with the cheap stuff.

 

If you have a stock engine you should be just fine with 87.
If it knocks or pings, you timing is off, you kock sensor is bad, or you have bigger problems.