Opinions On Gasoline Octane To Be Used?

[kevinmlexus]

Any opinions on this? In my last car (99 v6 mustang - ran great for 11 years), I used 89 octane, and used Exxon 99.9% of the entire time I drove it. The one time I decided try to gas from one of the big box warehouse stores, it knocked and pinged until I got Exxon back in it. I figure my RX 350 engine should be in a different class from a Ford Mustang, but wanted to see what opinions are out there. I know the manual recommends 93.

Thanks!

[BadBrad]

Any opinions on this? In my last car (99 v6 mustang - ran great for 11 years), I used 89 octane, and used Exxon 99.9% of the entire time I drove it. The one time I decided try to gas from one of the big box warehouse stores, it knocked and pinged until I get Exxon back in it. I figure my RX 350 engine should be in a different class from a Ford Mustang, but wanted to see what opinions are out there. I know the manual recommends 93.

Thanks!

87 all the time here - and I live in a HOT summer climate.

[pauljcl]

Any opinions on this? In my last car (99 v6 mustang - ran great for 11 years), I used 89 octane, and used Exxon 99.9% of the entire time I drove it. The one time I decided try to gas from one of the big box warehouse stores, it knocked and pinged until I get Exxon back in it. I figure my RX 350 engine should be in a different class from a Ford Mustang, but wanted to see what opinions are out there. I know the manual recommends 93.

Thanks!

87 all the time here - and I live in a HOT summer climate.

I am astonished that Lexus would recommend (require?) 93 octane. My 2009 RX350 requires 91 octane, which is available across the US, whereas I thought 93 was not so available....

I use 93, sometimes topping with 89 (mid-level), the average being 91 or above... I have noticed no difference with the lower or higher-octane tankful, which is at it should since it is always > or = 91. I don't drive that many miles with the car (nor with the BMW, which also requires 91 octane), so the 'extra cost' is immaterail.

[The G Man]

I though the RX requires 91 octane.

[kevinmlexus]

I though the RX requires 91 octane.

Yes, you're correct....typo in my original posting

[The G Man]

I though the RX requires 91 octane.

Yes, you're correct....typo in my original posting

I would use what ever Lexus requires, using 89 octane is not going to save you much money.

[BadBrad]

I though the RX requires 91 octane.

Only "required" to squeeze out that last three horsepower. Runs perfectly fine on 87.

[The G Man]

I though the RX requires 91 octane.

Only "required" to squeeze out that last three horsepower. Runs perfectly fine on 87.

Does it say that on the manual? No it doesnt. If it is ok to use 87 permenently, Lexus would have told you so.

I am sure you can put in cheap Kmart engine oil in yout Lexus and it will run too, but why would you want to treat your car like that?

[SLORICK]

Some idiot once told me: Just put Regular in it, and the ECU computer will adjust for it and make it run fine.

I think that is like the sign i saw in a motorcycle shop: "If you got a $10 head, then buy a $10 helmet"

Original Poster DID say his experience was with a 99 Mustang V6

When an automaker RECOMMENDS something (PREMIUM), who am I to question their engineers?

I am no "engineer". Just because Kerosene is cheaper, and Water is free, I am not going to put THEM in my Lexus either, but the idea of higher octane Airplane Racing Fuel for a boost has tempted me... I could win $10,000 on America's Funniest Home Videos too, if I video my attempt. . . or "World's Dumbest..."

[The G Man]

Some idiot once told me: Just put Regular in it, and the ECU computer will adjust for it and make it run fine.

I think that is like the sign i saw in a motorcycle shop: "If you got a $10 head, then buy a $10 helmet"

Lol, thats a funny one.

While it is true that the computer and the knock sensor will adjust to the lower octane, the engine will have to start knocking before it adjust the timing. The knocking might be so slight that you will never hear it or feel it, but none the less, it is knocking. The problem is that when the computer pull back timing to adjust for the lower octane, it will slowing advanve timing until it senses knocking, at thet point, it will pull back timing again. The cycle repeats itself time after time. Over time, this slight knocking may or may not cause damage to your engine.

[BadBrad]

I though the RX requires 91 octane.

Only "required" to squeeze out that last three horsepower. Runs perfectly fine on 87.

Does it say that on the manual? No it doesnt. If it is ok to use 87 permenently, Lexus would have told you so.

I am sure you can put in cheap Kmart engine oil in yout Lexus and it will run too, but why would you want to treat your car like that?

G-Man, lets really read from the manual, shall we? Let's see.... hmmm.... here it is... page 606..."Premium unleaded gasoline with an octane rating of 91 or higher required for optimum engine performance (emphasis added). If 91 octane cannot be obtained you may (emphasis added) use unleaded gasoline with a rating as low as 87. Use of gasoline with an octane rating lower than 91 may (emphasis added) result in engine knocking. Persistant knocking can lead to engine damage and should be corrected by refueling with higher octane unleaded gasoline."

I take away from this that you can use 87 so long as you don't experience engine knocking. Now I know engine knocking; my 1970 iron headed 10.5:1 compression ratio Buick knocks like it is full of monkeys with hammers on a 100 degree day running 91 octane. I detune it on a hot day from the driver's seat with an MSD Timing Controller http://www.msdignition.com/Products/RPM/Ti...ng_Control.aspx. I'm not nearly as fast or as accurate as the knock sensor on the Lexus but the pistons and connecting rod bearings in the Buick engine (seen for the first time in 14 years last year during a freshining) were beautiful even after getting hammered for 14 summers. I've been in many, many engines over the years and Toyota engines are over-engineered compared to the 40 and 50 year old stuff from the musclecar era.

I've never heard knocking or even light pinging from any of the three RXs I've owned, always running 87 and always with the same cautionary language in the owners manual.

There is no "prohibition" against using 87. I own stock in several big oil companies so I'm perfectly happy if you guys burn money needlesly to fund my retirement. I'll keep using 87 in the Lexus all year long and wish I could afford $6+ 104 Rocket Brand or Sunoco for the Buick in the summer.

Kmart oil (if they sell SM rated 0w-20) is perfectly acceptable and produced by one of the big oil companies - not Kmart. I always use Toyota oil and filters; they are competitvely priced and easily obtained.

[The G Man]

G-Man, lets really read from the manual, shall we? Let's see.... hmmm.... here it is... page 606..."Premium unleaded gasoline with an octane rating of 91 or higher required for optimum engine performance (emphasis added). If 91 octane cannot be obtained you may (emphasis added) use unleaded gasoline with a rating as low as 87. Use of gasoline with an octane rating lower than 91 may (emphasis added) result in engine knocking. Persistant knocking can lead to engine damage and should be corrected by refueling with higher octane unleaded gasoline."

I take away from this that you can use 87 so long as you don't experience engine knocking. Now I know engine knocking; my 1970 iron headed 10.5:1 compression ratio Buick knocks like it is full of monkeys with hammers on a 100 degree day running 91 octane. I detune it on a hot day from the driver's seat with an MSD Timing Controller http://www.msdignition.com/Products/RPM/Ti...ng_Control.aspx. I'm not nearly as fast or as accurate as the knock sensor on the Lexus but the pistons and connecting rod bearings in the Buick engine (seen for the first time in 14 years last year during a freshining) were beautiful even after getting hammered for 14 summers. I've been in many, many engines over the years and Toyota engines are over-engineered compared to the 40 and 50 year old stuff from the musclecar era.

I've never heard knocking or even light pinging from any of the three RXs I've owned, always running 87 and always with the same cautionary language in the owners manual.

There is no "prohibition" against using 87. I own stock in several big oil companies so I'm perfectly happy if you guys burn money needlesly to fund my retirement. I'll keep using 87 in the Lexus all year long and wish I could afford $6+ 104 Rocket Brand or Sunoco for the Buick in the summer.

Kmart oil (if they sell SM rated 0w-20) is perfectly acceptable and produced by one of the big oil companies - not Kmart. I always use Toyota oil and filters; they are competitvely priced and easily obtained.

BadBrad, I guess if you read the manual hard enough, you can read into it what you want it to mean. The manual said 91 or higher is required for optimum engine performance, do you really want to run your engine at below optimal condition? If 91 octane cannot be obtained you can use unleaded gasoline with a rating as low as 87, are you having problem finding 91 octane?

Listen, you can use 87 octane and chances are you will not damage anything in your Lexus. Personally, I just don’t see the point of taking that risk for a saving $3 a tank full.

[Tomcan]

Your vehicle may run OK on lower octane fuel and as long as there is no knocking it should not hurt the engine. However, power output and efficiency in one way or another is lower with the lower octane. The refining process is the key factor in achieving octane rating, detergent additives and octane booster are added to meet rating listed on the pump. One of the advantages of Sunoco 94 is better refining which reduces need for octane booster and a premium detergent additive to keep injectors and intake valves cleaner. No matter what octane you use, fuel injector cleaner added every 5,000 miles will keep the injectors clean and operating efficiently.

FYI: Most fuel stations have two tanks (high & low) and what comes out of the pump is a blend. Ethanol blended fuels have a reduced energy content, your bang for your buck is less. Ethanol may be green but it's a green gimmick.

[SW03ES]

Only "required" to squeeze out that last three horsepower. Runs perfectly fine on 87.

This has been debated on this forum...and every other forum ad nauseum...and I don't want to get into it on here again it always turns into a flamewar so I am going to close this.

One final thought. Yes your car may run okay on 87. Probably even. However...it is nearly a $50,000 automobile and how much more does premium really cost, $.20 a gallon? Lets say you fill up 18 gallons a week...thats $3.60 a week...$14.40 a month. Is it worth spending an extra $14.40 per month to know that you are putting what the manufacturer really reccomends in your $50,000 automobile? Thats a question you will have to answer for yourself.