I dont think there would be any real damage done. Just dont use 87. I read the results of a study that found most cars do fine with 89, but as the car ages they found that it was better to switch to 92.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>