You can't even get 88 octane in our area.87,89,91 at a few places,and 93. Back to your question,if a car calls for 87,that is 87 minimum.You can always go higher.

 

I burn mid-grade and premium in my `97 LS. Add sea foam every now and then too. Gas milage is better and she comes off the lights a bit quicker too. Know this, I read a story about gasolines and now all gas has only a storage life of about 3 months instead of the usual 6-8 months. Plus mid-grade and premium have better additives for keeping fuel clean...a must for fuel injection.

 

I guarantee you were knocking... you won't FEEL a difference, but you were definitely pre-detonating... alot of guys running 91 on a stock pulley will knock.. let alone 87...