There's an entire thread devoted to that question over here:
Originally Posted by jarhed1964
what am I saving by using 87? Maybe $2.50? $3.00? About $12-15.00/month? Is it worth it?
- What are you actually saving/losing by using 87 vs 91 octane AKI (1)
The net cost savings that can easily be calculated is somewhere around a thousand dollars per hundred thousand miles - but it's way more complicated than that so see the thread for details.
Last edited by bluebee; 11-24-2011 at 10:44 AM.