Octane Rating

[hkeller]

This has been discussed a bit on this board before. However, once and for all, can someone tell me if I can run 89 octance in my wife's 2000 LX 470? I heard that Porche recently announced that their previous recommendations to run "premium" fuel were unnecessary, as the engine management computer in their modern fuel injected cars compensates for lower octane.

Any thoughts? At about $2.50 per gallon, it is mighty hard to pull the trigger on the premium pump.

Thanks.

 

[tabraha]

My wife runs only 87 in her Tundra (same engine) every time she fills up. Runs just as good as the day we bought it. I run 93 in my LX though just because it gives me a little bit of a warm fuzzy feeling and I plan on running it into the ground so I would like to put that off as far as possible. It doesn't run any better than the Tundra though.

Tad

 

[hkeller]

What year is your Tundra? I heard they changed the timing map a bit in 2001, which allows them to run lower octane.

 

[tabraha]

Her's is an '02, but there are plenty of folks over at Tundra Solutions running 87 on the prior models.

Tad

 

[ebod]

The owners manual for my 2004 says that the car will run fine on 87 octane, but says that it will perform even better with 91. I haven't filled it up yet (it's a week old), but I'll probably use at least mid-grade until the novelty of a new car wears off.

 

[jjbodean1970]

yes, you can run 89 octane in your 2000 lx 470. premium is recommended by lexus, but factory reps have told me mid-grade is ok to run in my gs 300 (premium is also recommended), so should be fine in your lx, too. i try to cycle in a tank of premium every once in a while, however, but it's been getting less and less frequent!

jeff

 

[jjbodean1970]

ps, in 2001 they changed the requirement on lx 470 to run on regular unleaded, unsure of the reason for the change, but it's been 87 octane ever since 2001. 98 to 00 it was premium

 

[Landpimp]

I run mid grade in my 2000 UZJ(which says run premium), seems to like it just fine.

 

[mtycruiser]

I have used 87,89 and 93 octanes in my truck, works fine with either one. No noticeable difference in power or fuel consumption. no signs of pre-ignition either. I guess the computer range is wide enough to compensate for the chnge in gas grades.

 

[robbie]

THe computers in those model years are real quick and will comentsate for the fuel used. For best performance 91 is reccomended. You will need to remember that if a engine was designed for a certain fuel and if you run it on anything less the computer will shift timing to adjust for any knock the sensors detect, this happens so fast you will never detect the knock.
As for the cruiser VS tundra. Both v-8 but have different computers and software, they are tuned different. You can not assume that what is good for one is good for the other. They have had problem running SC on Curuiser where on Tundra's all have been fine. The crusier need some differnent Tuning and a extra injector for all to be fine( this was a few months ago). later robbie

 

[greglomax]

I got to looking at the owners manual for my 98 now that gas prices have gotten so high. It says that premium unleaded is required for that engine. An octane less than than that may cause pinging, which we all know is not very good on an engine because the gas is not being burned efficiently. I generally look for any reason to go the cheaper route on gas, but I am not comfortable in doing so with this vehicle.

 

[jjbodean1970]

dude, run the mid-grade, my peeps at lexus said it's fine!

 

[robbie]

I was talking to a rep for toyota on friday and I had something unusual for me. The block on a 100 k mile engine was worn in the ring grove area real bad. It is the only block I have seen like this. I asked him if he had seen this and what caused it. His answer was poor gas and oil quality. With toyota low tension rings it allows carbon to get behind the ring more thus pushing the ring into the cylinder wall, creating a deep groove over time. I personally have never seen this on any engine I have owned. I can attribute this to good oil, the right ocatane quality fuel. I have never run less then the Manufacture calls for, usually the next grade up (I tune my engines for more power). This will be a good test on what can happen if you run less octane then what Toyota sugests for your engine and EFI system. later robbie

 

[tabraha]

Oh nasty!!! Thanks for the info.

Tad

 

[Kaderabek]

So basically you're saying that adhering to the octane ratings is the safe thing to do?

I have another question as well. I've been running a tank of 91, then a tank of 93, switching back and forth (at an alarming rate). The first question notwithstanding, I'm not so sure switching octane like this makes sense, in that the computer adjusts for it each time. I'm sure there must be some subtle difference in how the truck runs between the octane ratings, but it's not noticeable to me. So is it a better idea to give the computer a break and just stick to one octane?

TJK

 

[robbie]

Really just stick to the octane that it is rated for. really try not to go less. Going more really does not have any benifit unless you are forced induction. On a 100 series you have not ablity to play with the timing unless you have sent the computer in to mess with the chip and reprogramm it. Going less on octane can contribute to some problems I mentioned before. Your engine (v-8) is a 10 to 1 or 9.8 to1 compression ratio (if I remember right. Pretty high ratio to run on pump gas uless you have the computer control the knock. So it happen so fast that it takes a computer. later robbie

 

[Kaderabek]

Great... now I own two Cruisers that want to drink high-test.

Thanks!

TJK

 

[98LXand99LC]

Great... now I own two Cruisers that want to drink high-test.

Thanks!

TJK

I'm right there with ya. But, as I tell my wife....it's a small price to pay to drive the best vehicles on the planet! Besides, I tell her, if you want gas mileage I'll trade your LX in and get a prius. "No thanks," she says.

 

[Kaderabek]

Right on.

TJK