altwyc88 Posted September 23, 2009 Share Posted September 23, 2009 HiAll !!! Just got a 06' 400H 'pre-owned'... so far, loving it !!! So what's the story on using 91 Octane for gas ? Is it recommended but not required ? What if I was to use 87 Octane ? Do not want anything mechanical to fail or for my warranty (for what's left about 7k) to be voided... Please share your experience. THANKS! Quote Link to comment Share on other sites More sharing options...
cduluk Posted September 23, 2009 Share Posted September 23, 2009 The manual recommends using a mid-grade gas or higher, but it's been proven 87 will work just fine. Your mileage just might suffer a tad, that's about it. And you might have to worry about the fuel filter and sensors going early down the line, but probably won't outweigh the difference in gas costs. Quote Link to comment Share on other sites More sharing options...
RX400h Posted September 24, 2009 Share Posted September 24, 2009 I use regular in the winter/cool months and mid grade during hot Summer months. Of course, "hot" is a relative term. If I were to drive to Las Vegas or Phoenix, I'd switch to premium. As a general rule-of-thumb, the colder the ambient temps, the lower the octane that can be used without adverse effects. Quote Link to comment Share on other sites More sharing options...
katzjamr Posted September 24, 2009 Share Posted September 24, 2009 yes the 400h will run on regular or premium, premium will give you more power and better gas mileage so that the extra cost is usually mitigated by that higher mpg. i prefer the better engine response of the higher grade fuel. This is a little bit of a sore subject, kind of like but not as contentious as the 'what kind of oil is best' debate. if you do a search you will find this is a frequent question asked here. when the 400h first came out some were upset that a 'green' car needed premium fuel and wanted to use regular. also i believe the first Lexus manual for the 2006 400h was not as strong in recommending premium as later years. The reality is this engine was designed to run on a higher octane fuel, you can use regular if you want, i have tried both but went back to the premium. It takes about three tanks to fully notice the difference one way or the other. Quote Link to comment Share on other sites More sharing options...
jrober Posted September 25, 2009 Share Posted September 25, 2009 This is a controversial topic but I have never been convinced that high octane fuel is needed in the Rx400h. I definitely don't believe that you get better mileage (and more energy) out of high octane additives. My personal experience matches this belief. As per my thread from last week, I have averaged 32.5 mpg this summer on low octane fuel. I have not done any better with high octane gasoline. I will continue to buy low octane fuel for my Rx400h (with my dealer's blessing) but to each his own. Quote Link to comment Share on other sites More sharing options...
Gryphon Posted September 25, 2009 Share Posted September 25, 2009 If I am not mistaken, the owner's manual wording for fuel requirement is different for each of 2006, 2007, and 2008 RX400h's. Tom Quote Link to comment Share on other sites More sharing options...
cduluk Posted September 25, 2009 Share Posted September 25, 2009 My 08 manual suggests premium. Quote Link to comment Share on other sites More sharing options...
BadBrad Posted October 1, 2009 Share Posted October 1, 2009 Ran 38k miles on 87 octane California gas in 100+ degree summers; never disapointed with performance; never any pinging. I think the math likely would indicate alleged nominal increase in fuel mileage cannot mitigate 20 cents per gallon higher fuel cost. Quote Link to comment Share on other sites More sharing options...
removeum Posted October 7, 2009 Share Posted October 7, 2009 2007 owners manual states premium 91 Octane. Quote Link to comment Share on other sites More sharing options...
BadBrad Posted October 9, 2009 Share Posted October 9, 2009 2007 owners manual states premium 91 Octane. Can you give us the exact quote from the manual? What you've written is ambiguous, in my oppinion. Quote Link to comment Share on other sites More sharing options...
removeum Posted October 10, 2009 Share Posted October 10, 2009 Page 414 of the 2007 RX 400h Owners Manual states" Premium unleaded gasoline with an octane rating of 91 or higher required for optimum engine performance." It also states"If premium gasoline is not available, you may use unleaded gasoline with an octane rating of 87." Quote Link to comment Share on other sites More sharing options...
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