DennisMik

You are not hurting anything. As you said, the computer will retard the timing so that you don't get pre-ignition (pinging) and harm the engine.

You lose a tiny bit of power and gas mileage from the lower octane. Most people can't tell the difference, although there are always debates going on as to how drastic these loses are and whether you will or will not be able to tell the difference.

I always run 87 octane in my cars. I have on occasion filled up with premium and I can feel the difference on pedal-to-the-metal acceleration. People will tell me I'm crazy, that it is all in my head. And the debates go on.

aawon

Greetings, greetings.

First time Lexus owner (2006 rx 330) and pretty hyped, not gonna lie. I have a question concerning fuel octanes, as I’ve already scoured this board and plenty others across the web.

Both vehicles have the same engines, however on the official Lexus site and fuel.gov site, the 04 takes 87 fine while the 06 highly recommends 93.

I purchased the car with 141K miles and do not have a clue as to what the previous owner put in the car.

What at I’m asking is, why is that the 04 recommends 87 octane and the 06 recommends 91 or higher?

I was thinking about getting the ECU reset and putting in redline for a fresh start. What do y’all think?

DennisMik

Both cars will run just fine on 87 octane. Why they changed the wording - who knows. The car's computer (ecm) will adjust the timing automatically without needing to be reset.

fabchef

hi gang, i've had my 2009 rx350 (with 118k miles) for a few months now. I know that it says to use premium (91 oct) fuel. I usually use premium on every 2nd or 3rd fill up, and regular on the other.
My take on it is that i find that running regular fuel is just a "peppy" if not a little more than premium and get the same if not slightly better milage with regular than the premium.
is this just me? do these cars really need to run on premium? i mean, i know they can run ok on regular gas, so is the premium a must?
thanks
fab

lexsc4

I have always use premium in my wife's 08 RX350 (135K miles now). I remember one time my wife put in regular and I did not feel any difference.

matts6887

Actually; it is best to go with what lexus reccomends; and the label on the inside of the tank lid of my rx350 says premium only. I did try going to mid grade a few times but I wasnt getting nearly the gas mileage i should be; so i went back to premium and have been using it ever since. I did just change out the front and rear spark plugs so that helps a little as well with the gas mileage and now Ive been getting closer to 21-23 highway and a little less in city driving.

spinellib

My RX350 manual says to use 91 Octane or higher but...

page 433: "If 91 rating cannot be obtained, you may use unleaded gasoline with an octane rating as low as 87."

What does the RX330 manual say?
What type of gas do you buy?
Have the gas prices changed your buying habits?

I filled up at BJ's gas station with their regular 89 octane, and I got lousy MPG's. Like 23 instead of 25 on the same (mostly highway) trip I do every day.

MattRX

Tried 91 in my Highlander (RX300 equivalent) and RX350 and the MPG increase was negligible at best. Not worth it for the price increase where I live, 0-60 time was the same as well.

Felix

I run 91, 92 octane......Most of the vehicles I've had were premium fuel burners......Yeah it costs more,IIRC the mz3's use regular fuel, but get slightly less mpg....Being the 2gr has vvt on the exhaust as well a variable length i/m runners, same as the svt focus, mzr 23 Mazda motors, as well as a few Honda motors. The 6.4 Hemi's also offer that as well..where the long runners are for the low end & then switchs over to the short runners for top end power. Premuim fuel is a cooler burning fuel compared to regular fuel as well..The flame front is slower w/ premuim vs regular.

shahir18

iTrader: (2)

https://support.lexus.com/s/article/...rade-shou-8129

TheGoodGuy

Depends on the station. At one station nearby I run 87 and it's great. At a different station their 87 will clatter so I run 89 if I buy there. 91 is unnecessary in our engines.

I also will never use ethanol. All of my fuel is 100% gasoline.

Felix

That'd depend on what engine your running......2gr, 1uz, 2ur......premuim only.