I have run my 05 V6 on 87 with no pinging or knocking. The need of using higher octane is a whole topic by itself. If the engine does not require to run on high octane gas, then it's fine by just regular(87,89). FYI: Lower octane gas is actually easier for spontaneous ignition. Higher octane gas is harder for "spontaneous pre-ignition", thus prevent knocking or pinging. It does not give you performance gain, if your engine doesn't require it for its optimal performance.