I just bought a 2004 V8 Limited. About gasoline, the manual says the minimum octane rating should be 87 but for improved performance they recommend 91. I've never seen anything like that before. In my Hondas they always said simply 87 was the minimum.so I always used regular. In my Audis they said 91 was the minimum, so I always used super. What do they mean by "improved performance" from 91?. What specifically would improve, and does that mean that 89 is better than 87 but not as good as 91? Also what do you guys use? Thanks Dan

Dan, I never really paid attention to my 4Runner's gas recommendation, but have always used 87, with absolutely no problems. It is a V8 also, with 33K miles. When we bought our Honda Odyssey, they told us the engine was rated at 210HP using 91 octane. They said using 87 was just fine, but it dropped the HP rating to 205. Once again, we've used 87 for the life of the vehicle with zero problems. My 99 Maxima did run noticeably worse on lower octane, so I surmised it must be related to the sophistication of the engine management computers used. The Maxima was really 1994 technology as it was pretty much unchanged since introduction in late 94. Both the Honda and Toyota are of the latest generation. Again, this is pretty much speculation on my part, but I can't think of anything else that would make that big a difference, and compensate for the different octane ratings. Thanks, Andy

My manual says the same thing which is curious. Engines are made to run on a certain octane so I don't understand how my V6 would benefit from higher octane unless their are sensors or something that makes an adjustment to the timing. I've used 89 and 91 and so far, the mileage is the same, about 18 most of the time, with 21-22 the best when driving long distance. I put premium in it when I am trailering the boat but, like you, I would like to know why I should. Now that gas is down to the "cheap" price of $1.75/Gal for regular, I am experimenting with premium again having filled up at a Shell station last night. I will run the next 1,000 miles or at least 4 or 5 tankfulls in premium and let you know the result. I calculate mileage every fill-up so I am very in tune to it. If it gets better mileage, then it is cost effective and burns more efficiently. If it doesn't, I will go back to 87 octane and never look back. I am interested to read the other responses. This much I know, you do not NEED to run anything but 87.