depends if its stock or not and if its SC/Turbo charged.
Now on a stock motor like yours it shouldn't be more than 9:5.1 compression so just use 87 oct fuel. If you incresse the compression more than 9:5.1 or add boost to incresse compression you will need to run 91-93 oct fuel.
***Now I've had a motor and see some that has for some reason ran a whole lot better on 89-91 oct gas when they was made for 87 oct gas. So if you car runs like crap on 87 try 89 and see what it does. You would be wasting your time and WAY more money by using 91-93 on a motor not made for it. Just to give you a heads up and I hope that helps.***
Actually it is the exact oposite. If you run 93 octane when you only need 87 you will get your combustion chamber dirtier, not cleaner. A higher octane gas has a higher combustion preassure so if the compression isn't there, then some of it goes underburned and could leave deposits on your valves. Running a 2 higher octane can be better just because the quality of gas could be better. I stress "could" not will. Btw, for all of you who are stuck in the whole brand name gas ideal, I'm going to clue you in. One day go out to a gas sump and watch all the tankers that go in and get gas. You'll notice that shell, chevron, exxon, mobil, they all grab their gas out of the exact same tank. And if you follow the tanker all the way to the gas station, you will see that no additives are added between the sump and the ending station. So all this chevron with techron crap, and all the other companies bs additives are just that. The only thing that i could think of is that the additives were added to the entire sump. This means that every tanker that gets gas from there will get the good gas. So whether you get shell or chevron, it doesn't matter. Btw, im not sure about the cheapo brand gas. I think they have their own sump. Like kroger, wall mart, race track, and all the lower brands have their own sump seperate from the big name sump. But i'm not sure of this. They may get their gas from the same dang sump as everyone else. Who knows. I've only done minimal research on this topic. Once again, I have answered a question no one asked!