The manual says 91+ but I'm wondering if anyone has comment on using 87/89 on most typical driving? Will it hurt the car or just less performance or less mileage?

 

The higher the octane the more resistent it is to engine knock. High compressioon engines generally are more prone to engine knock, thus need higher octane gas like premium. Most high end cars in the last 10 years use anti knock sensors to help prevent engine knock. What these sensors do is listen for the sounds of engine knock, and if detected do a number of things like retard ignition timing. This protects the engine, but also reduces power. Since the RX350 recomends premium, it will work best with it. It will; however, work with lower octane gas because of these anti knock sensors. Depending on your driving style, ambient tempeture and other vairables many people will not feel any difference, but some owners will. I personally get better over all MPG using premium on our RX330. You should just give it a try and see what happens.

 

My personal experience, with an '01 Highlander, and '04 and '05 RX330s is that the increase in mpg more than makes up for the price differential, so I consistently used 93 octane in those vehicles.

 

Use 87 in my 400h hasn't hurt the car nor have i felt any performance issues. Ocassionally i will put in 93 but i think it is just to habit because i'm use to putting 93 in my previous cars. Just got an IS350 haven't decided on what i will do. But it all depends on the owner, if the manual states 93 and it makes you feel comfortable then what is the extra $2. Will you notice a difference i highly doubt it.


Ken