I purchased my 98 GXE with 37k on the odometer. I later found out the car was registered as a rental Car with Avis. Who puts high octane gas in a rental?!!! I know I don't!!!
I've got 147k on the odometer now. The first 5k that I had the car, I used 93. Afterward, when gas prices started creeping up I talked to a certified nissan mechanic (who is now my personal mechanic on all 3 of our Nissans). He said that the reccomendation for high octane is only a recommendation and not a requirement. He said the car will be fine so I opted for 87 and have been using it ever since. There is a slight performance decrease and slight decrease in fuel economy but the way gas prices are today to me it's not worth the extra money for the 93 and the car still runs good.
I find it hard to believe that after more than 100k all that 87 that I put in the car was really 93.
If a certified Nissan mechanic says my car will run on 87 with no problems, he uses it in his Nissan, and I get 100k out a used car using
87 then it's probably okay to use 87.Unless a car is highly modified I don't think using 87 is going to harm the car.