Premium fuel ? (2 Viewers)

[Pandaman]

I have been kicking around getting a new GX 460. I read on a Lexus dealerships website that it needs to run on 91 octane. Is that true or just their suggestion. The salesman I spoke to said that it was not true but he wants a sale.

Thank you

 

[Docyota]

I have been kicking around getting a new GX 460. I read on a Lexus dealerships website that it needs to run on 91 octane. Is that true or just their suggestion. The salesman I spoke to said that it was not true but he wants a sale.

Thank you

I've used 87 occasionally by accident, and once in a while when it was the only available. But the sticker inside the fuel door says only premium (91 or above), and I've heard of engine knocks and such without it.

And if you're looking at a new $65,000 vehicle, 20-40 more cents per gallon (~$4-8 per tank) really shouldn't be a big factor to you.

 

[ericm979]

You can find huge arguments about this on other sites.

Modern FI engines have knock sensors which will add fuel or cut ignition advance or both when knock is detected. The amount of knock that can trigger this is well below what you can hear or feel. Many OEM ECU tunes aim for just knocking a little at cruise throttle in order to maximize fuel economy and rely on the knock sensors to protect the engine under load.

The ECU programming that controls this has an operating envelope. It can only cope with a certain amount of knock. The problem is that (to my knowledge) no one who knows what Toyota's US market ECU tune is has said in public what it's tuned for. It's possible that Lexus speced 91 merely to make the car seem more upscale and it will totally run fine on 87 when towing a 6500lb trailer out of Death Valley in August and any other heavy load situation. Or they speced it because 87 can take the tune out of the envelope in some situations resulting in potentially expensive engine damage. I've yet to see any definitive info on this, just lots of conjecture. And I dislike expensive engine damage. So I run premium.

 

[Roody]

You can find huge arguments about this on other sites.

And on this one... Maybe not argued, but certainly debated.

GX460 KCLV for premium vs regular gas

So - in my pursuit of trying to figure out regular vs. premium gas use for my GX460, I got myself deep into the rabbit hole that is the Toyota/Lexus ECU mapping for injection timing in trucks, how Toyota engines calculate injection timing, and how the knock feedback works. I can’t find any info...

forum.ih8mud.com

GX460 ECM Remapping for Regular Gas?

Hello Brain Trust! Do any of you know of anyone who's remapping the 4.6L ECM to allow use of regular unleaded gasoline?

forum.ih8mud.com

Fuel ?? 91 vs 88 octane ??

In Utah that's our options......other than regular 85 for the Tacoma What octane are you running in your GX 460 ? I'm @ 6000' elevation in Utah Do you see a performance difference running 91 opposed to 88 ? Just for the record....Costco (2 hrs away) 91 was $1.99 a gallon Sunday !! what a...

forum.ih8mud.com

There's no definitive answer, the manual recommends premium so that's what most of us run, but the ECM and engine itself are built to handle low-octane stuff from around the world should it come to that. YMMV, fuel at your own risk, yada yada yada.

 

[xychromosome]

This is a common debate with plenty of argument for both sides. Bottom line, at least for me, is how would you react to buying a GX knowing that the previous owner used only 87 octane fuel?

 

[r2m]

I have personally found I get better MPG with 91 than regular. And when we went cross country a couple years ago, east of the continental divide where premium is closer to 95 octane, my MPG bumped up another couple of miles per gallon.
So you can either save at the pump or get a little more range from a tank of gas. Not quite an even swap but, but 6 of one, half dozen of the other.
I'll take more miles per tank. For me the BIGGEST waste of time in my life is pumping gas and waiting in lines.
So, yeah, I'll spend the extra change on premium.
If you think about how much more per tank premium is over regular, it's about a cup of Starbucks (or less). And that cup of Starbucks isn't everyday, it's only when you fill up!

 

[Rednexus]

I ran premium in my 470 (different engine I know) during COVID when it was <$2/gallon. I switched to regular 87 when gas crested $2/gallon and the $0.50/gallon extra cost just wasn't worth it. My 470, when stock, did have slightly more power on premium and got slightly better gas mileage. I actually don't think it's due to the octane at all, but due to 87 here in the Midwest always being 10% ethanol (thank you, ag lobby....) and premium being 0% ethanol (which is why I run it in my lawn mower, leaf blower, etc, as ethanol is very bad for small engines). Ethanol has a lower energy density than normal gasoline, so slightly reduced power and MPG should be expected.

I've since added headers, an exhaust, and CAI on my 470 and it was much more power on 87 with those mods than it ever did stock on 91. I also routine tow a 4,000# loaded camper with my 470, with my family of 4 inside. All on 87, no issues. IMO, save you money for something else, but premium is not going to hurt anything either. The 1UR only has 10.2:1 compression....our Highlander has a whopping 14:1 and runs on 87, a past Mazda I owned had 13:1 compression and ran fine on 87 as well and were factory-specified for it.

 

[r2m]

IMO, save you money for something else, but premium is not going to hurt anything either.

Like a cup of Starbucks on every tank fill?

 

[MotoDave]

As one data point the Tundra was available with the same engine with a marginally different rated power output, and does not recommend/require premium.

 

[Rednexus]

Like a cup of Starbucks on every tank fill?

Or more bags of green coffee to home roast

 

[BigSwede]

This vehicle has been in production for 13 years, and I have yet to hear of one damaged by running lower octane.

That said, I have run both and while it does fine on 87, it does seem a little happier (sound and performance) on 91. Conformation bias, possibly, but there it is.

 

[r2m]

Perhaps the statement by Lexus of requiring 91 octane is to lay claim to the higher MPG rating.
It would probably be a couple miles/gal less if they spec'ed out 87 and probably wouldn't go over well with a lot of customers considering how fuel conscious everyone is these days.

 

[Pandaman]

This is the link from my local Lexus dealer. When I sent it to the salesman that I had been talking with, he brought up how several people working there had them and ran them on 87 octane. In my part of Florida, you can buy 87, 89 or 93 octane.

https://www.lexusofclearwater.com/service/does-lexus-require-premium-gas/

 

[Acrad]

Not sure if fuel or tuning but 1UR-FE in Eurasian GX 460s are rated at 292HP

 

[120mm]

It's not as complicated as you think.

The computer will protect your engine from knocking caused by 87 octane gas. It will also reduce maximum power, especially under load or in high heat environments.

You will get slightly worse MPG running 87 than running 91.

You will get better detergent additives running premium at most brands.

I am normally a relative cheapskate when it comes to cars. But my local station has premium (93 octane) at only 10% higher than 87 octane, so for the increased power, MPG and better additives, plus the probability that we'll own this vehicle for at least a decade, if not more, I've decided on premium.

 

[mudwagon]

I wrote this a while ago...
Octane/Knock System
Has way more detail than you might need. Long story short 120mm nailed it on the head.

 

[120mm]

I wrote this a while ago...
Octane/Knock System
Has way more detail than you might need. Long story short 120mm nailed it on the head.

Yeah, that is one of the threads I read before I bought this rig.

 

[handwerk]

So if a person was to choose not to run premium but rather 87 are you better to stick with one fuel and let the vehicle "adjust" or is it better to put premium in once in awhile?

 

[mudwagon]

So if a person was to choose not to run premium but rather 87 are you better to stick with one fuel and let the vehicle "adjust" or is it better to put premium in once in awhile?

From a detergent perspective dumping a tank of premium in once in a while probably will help, but you could also just grab a detergent adder from a parts store and add that to your 87. BTW random sampling of 87 across the US is really closer to 88 than 87 according to some internal info I have at work, so most 87 is not nearly as low as one might think. That said top tier only is what I would put in: Shell, Mobil, Exxon, BP etc.

Either way you're not going to be operating at optimal spark control long term because the ECM will constantly be adding spark when there is absence of knock which means that once the knock events get heavy enough then it will retard spark again until the long term multiplier takes over and adjusts a semi-permanent multiplier, but that is always adjusting based on what is going on with the engine. This is why it would be better to tune the base hi map for 87 rather than just dump 87 in on a 91 map, so that you always stay at your base hi. The less intervention the more efficient everything will operate.

 

[Rednexus]

This is why it would be better to tune the base hi map for 87 rather than just dump 87 in on a 91 map, so that you always stay at your base hi. The less intervention the more efficient everything will operate.

I am probably going to get a YotaWerx tune package for my GX, with an 87 octane tune for normal use and a 91 octane tune for pulling our camper (when more power would be always nice).

FYI, I usually run Top Tier gas in almost all of our vehicles unless I'm in a pinch where I need fuel and only off-brand stations are around. Then I add a bottle of Techron at every oil change to keep things clean. My previous 13:1 compression Mazda 3 did definitely not like cheaper fuel - although I have not noticed any difference on our lower-compression vehicles.