I would say that our SHO is capable of running safely for may miles in 87. To get the best performance you need to run 93. From Ford's website: https://www.ford.com/cars/taurus/features/power/?intcmp=vhp-featcta-power It states the rated power was recorded using 93. Will you be able to notice a difference? Helifiknow. The car will just retard timing and not give you everyhing you paid for. Octane is the resistance to detonation. Higher the octane, the safer one is. But a properly working stock car should be fine on 87. I made reference to this in the other thread.