ScottB

I've been looking at the Lexus GX470 to replace my wife's Acura. Both her Acura TL and my S2000 clearly state that premium fuel is required. However, apparantly Lexus says that fuel is 87 octane, but 91 octane is "recommended". What is this recommended business? Is it required for engine knocking or not? How is one supposed to read into what recommended really means in this case?

Here is a link to that document:

http://pressroom.toyota.com/photo_library/...?id=2003gx470_s

99GT

The Lexus computer most likely retards timing based on engine sensors. If it detects knock from a lower grade of gas, it will retard timing. For maximum performance and mileage, use 91 octane or better, but if you have no choice, 87 octane would work.

Note it says 87 octane for "Requirement," meaning it requires at least 87. 91 octane is recommended because that is the highest octane the ECU is calibrated for, or to look at it another way, the ECU is calibrated for 91, but Lexus realizes some people are nickle-and-dimers (even when buying Lexus) and refuse to buy a car that "requires" 91, or ignore the factory recommendation and will fill it with 87 to save $.50-3.00 a fill-up, regardless how it affects the vehicle they paid $40+ grand for.

qwerty22

Most (if not all) new cars now automatically retard timing , reducing power if you fill up with low octane gas, no harm to your car, except maybe it won't go as fast when you put the pedal to the metal

ScottB

Thanks, guys. Honda/Acura seems a lot more emphatic about what is needed, than Toyota. I'm used to premium only, so no loss here.