Rx Fuel Requirement ?

[JackyNelson]

Just bought a 08 RX350, the book says, unlead 91 or above, is it meaning have to use Premium? here is $3.40 per gal currently.

I thought all new Cars can using Regular..?? :cries:

[wwest]

Just bought a 08 RX350, the book says, unlead 91 or above, is it meaning have to use Premium? here is $3.40 per gal currently.

I thought all new Cars can using Regular..??:cries:

Yes, almost all new cars, those with EFI, Electronic Fuel Injection, and knock/ping sensing, can use regular fuel.

Even both of those pictured to the left.

[ursa99]

My dealer told me that the RX350 will automatically adjust the timing depending on the fuel

you are using. That being said he also mentioned that using regular would result in lower

fuel cost, poorer performance and lower mileage. In the end it may be a wash in terms of

cost savings...

[wwest]

My dealer told me that the RX350 will automatically adjust the timing depending on the fuel

you are using. That being said he also mentioned that using regular would result in lower

fuel cost, poorer performance and lower mileage. In the end it may be a wash in terms of

cost savings...

"would result in lower fuel cost, poorer performance and lower mileage."

But does the lower mileage, MPG, exceed the lower cost gain??

And just how often does the average person use WOT, which is the only time lower performance would be noticeable, if even then.

[rx350guy]

My dealer told me that regular was fine to use in my new 08 RX 350, despite the fact that the owner's manual says premium, and so does the sticker on the inside of the refueling door.

Personally, I suppose it's probably okay to use lower octane fuel, but I'm following what the owner's manual says and using premium. So far, it's working very well; I'm getting good gas mileage (ave MPG 25-27 combined), and the car runs great. I see no reason to change anything at this point..

[jonnyheroes]

I would be interested in hearing the fuel, mileage and type of driving other members here get.

I find it hard to believe that this an RX350 gets 25-27 mpg unless it's 100% highway driving.

I use regular fuel, mostly drive in the suburbs (80% roads, 20% highways) and average about 18 mpg.

[Wilson2007]

I would be interested in hearing the fuel, mileage and type of driving other members here get.

I find it hard to believe that this an RX350 gets 25-27 mpg unless it's 100% highway driving.

I use regular fuel, mostly drive in the suburbs (80% roads, 20% highways) and average about 18 mpg.

My 2007 has averaged about 20 mpg (converted from l/100 km) over 25000 km of mostly highway driving. Sometimes when I have a good tailwind and keep speed around 110km/hr. I can get up to 26.5 mpg (8.5 L/100km) on the trip computer. All with premium fuel.

[dman98765]

Your Lexus dealer is wrong about mpg. Octane rating is simply a quantative figure to indicate the ingnition temperature of the fuel. Higher octane fuels are used for higher compression engines since the ignition temperature for gasoline decreases as the cylinder compression increases. Highere octane fuels prevent pre-ignition.

Pre-ignition (the pinging and knocking noise) is one of the worst things that can happen to your engine. It occurs when the fuel in the cylinder ignites while the piston is still traveling upward toward the cylinder head rather than igniting at the top of the piston travel to force the piston downward (the power stroke).

To find out if your vehicle will work with lower octane fuels:

Run your vehicle down to 1/8 th of a tank.

Fill up with 5 gallons of mid-grade (89 octane in my area).

Drive normally. If you feel any knocking or pinging, IMMEDIATELY top the rest of the tank with premium (91 octane in my area).

If no knocking or pinging occurs, your good to drive on that octane level.

Remember that different states have different fuel formula requirements. I had a vehicle that would knock in California on 87 oct. but ran fine in Florida on 87 oct.

[bobII]

The difference in cost for reg 87 vs prem 91 sounds like a lot when looking at per gallon cost. Here the price difference is $.20 / gal. If I drive 15000 miles per year at 20 mpg that's 750 gallons. At price difference of $.20/gal that works out to $150.00. For me I'll use the premium grade since that is what the manufacturer recommends.

[ernster]

i put premium in unless i have no choice. i average 20 mpg driving about 50/50 highway and city.

i don't mind it. my old expedition averaged 13.4 mpg and had a 30 gallon tank. that's 90.00 for regular at 3.00 a gallon. at my worst, i've had to put 50.00 in to gas up my car since i bought it last december.

[2005 ES330 Salvage Title]

Just bought a 08 RX350, the book says, unlead 91 or above, is it meaning have to use Premium? here is $3.40 per gal currently.

I thought all new Cars can using Regular..?? :cries:

Apply for a gas card that rebates 5%. If you can catch them at a promotional period, that number is usually much higher the first couple of billing cycles. Yes, this is the best / only way to afford premium fuel. I currently have a SHELL and Phillips Card that I ONLY use for fuel purchases. PAY the STATEMENT BALANCE each month and you never pay a penny in interest.

$3.40 - 5% (.17)= $3.23/gallon.

When I got both my Shell Card & Phillips Card, the promo was 15% for first 60 days, then 5% thereafter. So far I have saved an aggregate of $385 over two years.

-TiM

[JackyNelson]

Thank you for everybody's replies..

they are very helpful.. :D

[Nebraska99]

Thank you for everybody's replies..

they are very helpful.. :D

I dont mean to sound snotty but if anyone can't afford premium gas then they probably shouldn't buy a 42 thousand dollar vehicle.

[rx350guy]

Thank you for everybody's replies..

they are very helpful.. :D

I dont mean to sound snotty but if anyone can't afford premium gas then they probably shouldn't buy a 42 thousand dollar vehicle.

However, in today's world, being 'able to afford' premium fuel is a relative concept; what with the way gas prices are going these days. It is predicted to top $4.00/gal for REGULAR in my area before the spring/summer driving season is over... OUCH!! :(

[Dick_Lake_Tahoe_NV]

My Best estimate is that the total cost to own my new Lexus for 5-years and drive about 13,000- 15,000 miles per year is 82-cents per mile--So I'll pay an extra 20-cents/gallon for Premium--and get the best performance possible and my cost will rise to 83-cents per mile.

[fbsdmd]

My Best estimate is that the total cost to own my new Lexus for 5-years and drive about 13,000- 15,000 miles per year is 82-cents per mile--So I'll pay an extra 20-cents/gallon for Premium--and get the best performance possible and my cost will rise to 83-cents per mile.

I do not believe that using premium will give you the best performance possible, and I can afford to buy premium. What I can't afford is oil changes. You may find this difficult to accept, but in the great Northeast of the USA there are gas stations that don't have premium, and some that don't even have mid grade. We put 76,000 miles on our 2004 RX-330, and are up to 1500 miles on the 2008 RX-350. We have never used anything but regular. Neither car ever pinged or knocked, which is the key to the octane puzzle, and both got acceptable gas mileage. In addition, for both cars, we were specifically told by the dealer that regular was acceptable.

[SmilingBoognish]

To find out if your vehicle will work with lower octane fuels:

Run your vehicle down to 1/8 th of a tank.

Fill up with 5 gallons of mid-grade (89 octane in my area).

Drive normally. If you feel any knocking or pinging, IMMEDIATELY top the rest of the tank with premium (91 octane in my area).

If no knocking or pinging occurs, your good to drive on that octane level.

If you can actually hear a Lexus motor pinging through all the sound deadening material, you have already done significant damage. Modern engines, as alluded to above, are required by law to function on 87 octane. This is done by the ECU sensing knock and retarding timing. Read that again, the ECU has to "sense knock" before it makes any adjustment to timing in order for pre-ignition to be avoided. I plan on keeping my vehicle well past the warranty, and I'll gladly put the proper octane in my tank that the engineers intended. Bad things happen to engines running on lower octane than they were designed to for...this thread makes me glad I got a good deal on a new one rather than buying used.

[fbsdmd]

To find out if your vehicle will work with lower octane fuels:

Run your vehicle down to 1/8 th of a tank.

Fill up with 5 gallons of mid-grade (89 octane in my area).

Drive normally. If you feel any knocking or pinging, IMMEDIATELY top the rest of the tank with premium (91 octane in my area).

If no knocking or pinging occurs, your good to drive on that octane level.

If you can actually hear a Lexus motor pinging through all the sound deadening material, you have already done significant damage. Modern engines, as alluded to above, are required by law to function on 87 octane. This is done by the ECU sensing knock and retarding timing. Read that again, the ECU has to "sense knock" before it makes any adjustment to timing in order for pre-ignition to be avoided. I plan on keeping my vehicle well past the warranty, and I'll gladly put the proper octane in my tank that the engineers intended. Bad things happen to engines running on lower octane than they were designed to for...this thread makes me glad I got a good deal on a new one rather than buying used.

Yes indeed, you will definitely want to rely on the Lexus engineers.

[scottq60]

Thank you for everybody's replies..

they are very helpful.. :D

I dont mean to sound snotty but if anyone can't afford premium gas then they probably shouldn't buy a 42 thousand dollar vehicle.

I'm also guessing that same person isn't paying Lexus dealership prices for periodic routine maintenance either....

Seriously, just because one spends $40k+ for a vehicle doesn't mean they don't have a healthy respect for stretching their $$ as far as possible.

Will we run other than premium fuel in our RX to save money - NO! - I believe in abiding by the manufacturer's recomendations for the most part. Will we only buy our oil and filters at Lexus dealerships - NO!!! Not when there are cost-effective equivalent alternatives available.

I for one...will NOT take my wife's RX to the dealership for an oil change...does that mean we shouldn't have bought a Lexus???

I think not...all Lexus owners don't have "money to burn" or choose to waste it either... maybe I'm not "top drawer" enough to be a Lexus owner....pity!

[fbsdmd]

Just a little anecdotal evidence. I had a 2004 RX330 that was traded with near 80,000 miles on it. Never used anything but regular, never heard any pinging, no complaints about performance, no apparent damage. I now have a 2008 RX 350, only regular gas used in it for about the first 4,000 miles, same as above. I live in the great NE and we now have gasoline with 10% ethanol, all grades, no choice. I recently did two tests, using the MPG calculator on the dash. I realize that this readout may not give an absolutely correct MPG figure, but I think that comparison between MPG readings may be meaningful. The first test was done using regular gas with 10% ethanol and gas without ethanol. Ethanol containing gas was used to fill the tank so that the tank would be near empty after a 150 mile trip. The tank was refilled with gas without ethanol, and the 150 miles was reversed. The MPG readout was carefully observed during the trip, and the maximum MPG for each trip was recorded. I have been told that 10% ethanol will lower gas mileage as much as 2 MPG. Both legs of the trip yielded approx 24 MPG. Now as to test two. I have begun to use high test. Have been using it for the last 4 tank fulls. Today I repeated the same trip as in test one, using high test. Maximum MPG observed was 27.4. I was not able to detect any difference in performance during either test. I realize this is most certainly not an absolutely scientific testing regimen, but there may be a flash of facts here. My first thought is that 10% ethanol, at high, steady speed may not give a noticeable loss of MPG. Secondly, if high test gives a roughly 10% increase in MPG, and the difference between regular and high test is $.20 more than regular, at $3.60 a gallon for regular, you should save money by buying high test. I know, this is a sample of one, but it may have some validity. Thoughts anyone?

[Messerchmidt]

the 3.5L used in the RX350 uses the same 3.5Las the Camry, rav4, etc -> just with a lexus badge on the engine cover - its a lower compression motor so it can use octane87. Same as how the Old rx330's 3.3L used octane87.

The higher compression motors used the GS350 and IS350 need premium

[rx350guy]

Just a little anecdotal evidence. I had a 2004 RX330 that was traded with near 80,000 miles on it. Never used anything but regular, never heard any pinging, no complaints about performance, no apparent damage. I now have a 2008 RX 350, only regular gas used in it for about the first 4,000 miles, same as above. I live in the great NE and we now have gasoline with 10% ethanol, all grades, no choice. I recently did two tests, using the MPG calculator on the dash. I realize that this readout may not give an absolutely correct MPG figure, but I think that comparison between MPG readings may be meaningful. The first test was done using regular gas with 10% ethanol and gas without ethanol. Ethanol containing gas was used to fill the tank so that the tank would be near empty after a 150 mile trip. The tank was refilled with gas without ethanol, and the 150 miles was reversed. The MPG readout was carefully observed during the trip, and the maximum MPG for each trip was recorded. I have been told that 10% ethanol will lower gas mileage as much as 2 MPG. Both legs of the trip yielded approx 24 MPG. Now as to test two. I have begun to use high test. Have been using it for the last 4 tank fulls. Today I repeated the same trip as in test one, using high test. Maximum MPG observed was 27.4. I was not able to detect any difference in performance during either test. I realize this is most certainly not an absolutely scientific testing regimen, but there may be a flash of facts here. My first thought is that 10% ethanol, at high, steady speed may not give a noticeable loss of MPG. Secondly, if high test gives a roughly 10% increase in MPG, and the difference between regular and high test is $.20 more than regular, at $3.60 a gallon for regular, you should save money by buying high test. I know, this is a sample of one, but it may have some validity. Thoughts anyone?

I won't argue with your testing regimen, or the results; but your results do make me feel much better using high test; especially at today's outrageous prices..

[fbsdmd]

Just a little anecdotal evidence. I had a 2004 RX330 that was traded with near 80,000 miles on it. Never used anything but regular, never heard any pinging, no complaints about performance, no apparent damage. I now have a 2008 RX 350, only regular gas used in it for about the first 4,000 miles, same as above. I live in the great NE and we now have gasoline with 10% ethanol, all grades, no choice. I recently did two tests, using the MPG calculator on the dash. I realize that this readout may not give an absolutely correct MPG figure, but I think that comparison between MPG readings may be meaningful. The first test was done using regular gas with 10% ethanol and gas without ethanol. Ethanol containing gas was used to fill the tank so that the tank would be near empty after a 150 mile trip. The tank was refilled with gas without ethanol, and the 150 miles was reversed. The MPG readout was carefully observed during the trip, and the maximum MPG for each trip was recorded. I have been told that 10% ethanol will lower gas mileage as much as 2 MPG. Both legs of the trip yielded approx 24 MPG. Now as to test two. I have begun to use high test. Have been using it for the last 4 tank fulls. Today I repeated the same trip as in test one, using high test. Maximum MPG observed was 27.4. I was not able to detect any difference in performance during either test. I realize this is most certainly not an absolutely scientific testing regimen, but there may be a flash of facts here. My first thought is that 10% ethanol, at high, steady speed may not give a noticeable loss of MPG. Secondly, if high test gives a roughly 10% increase in MPG, and the difference between regular and high test is $.20 more than regular, at $3.60 a gallon for regular, you should save money by buying high test. I know, this is a sample of one, but it may have some validity. Thoughts anyone?

I won't argue with your testing regimen, or the results; but your results do make me feel much better using high test; especially at today's outrageous prices..

Sad to say, the difference between regular and high test today in New Jersey is $.38

[Chris Parker]

Sad to say, the difference between regular and high test today in New Jersey is $.38

Sad to say, but I only now figured out from this thread that "premium fuel" according to Lexus is 91 octane, not 93 octane, correct? Most stations where I live carry 3 octanes --- 87/89/93 --- so I've been buying 93. Now I'm going to start mixing 93/87 2:1 or 93/89 1:1 (whichever combination is cheaper, as the stations here also are not pricing the grades fairly so that it wouldn't matter) to get the required 91 octane and not overpay. Wish I'd figured that out this past summer when the premium surcharge was extreme, but that's water under the bridge now.

[Deepak Gandhi]

Thank you for everybody's replies..

they are very helpful.. :D

I dont mean to sound snotty but if anyone can't afford premium gas then they probably shouldn't buy a 42 thousand dollar vehicle.

Wrong - People buy expensive cars for convenience, reliability, and of course prestige. Don't forget that "money saved is money earned". It is very much OK to have the desire to save, be it on gas or any thing else....

However, in today's world, being 'able to afford' premium fuel is a relative concept; what with the way gas prices are going these days. It is predicted to top $4.00/gal for REGULAR in my area before the spring/summer driving season is over... OUCH!! :(