Fuel discussions/questions - Octane Regular or Premium (merged threads)
12-02-19, 01:19 PM
#391
Advanced
To summarize and repeat all the other regular vs premium threads on the GX and LX forums (there are quite a lot):
GX guys are split, with most tending to go with premium.
LX guys are split, with most tending to go with regular. Go figure.
Though these days it seems the GX guys are also now trending regular, probably a result of the car getting older/cheaper.
It's pretty settled that both GX and LX will not knock with any 87 octane product or better. I have not come across anyone on the internet or in person who has had knock running regular in a GX or LX (or Tundra or land cruiser for that matter). You may be able to find someone who has or thinks they have, but it seems there are countless owners reporting that they run regular with no issues.
On the other hand, you can find plenty of people with modern fuel injected cars that do knock when lower than recommended octane is used. E.g. for the Acura MDX this is a common issue, and I know first hand that my wife's MDX in particular will knock if you put less than premium in the tank.
For the GX, the only real arguments open for debate running regular are a perceived lack of performance/fuel economy, or a theoretical gradual wear issue and possible future repair bill. There are compelling arguments on both sides, but to-date there have been no reported incidents from running regular, and the 2nd gen GX has been running around for a decade now. Also FWIW nobody has put this to the test on the dyno either. So again, performance and wear are up for debate but nebulous at best.
That's the thing. On both the GX and LX, Lexus requires premium, but for the exact same motors in their Toyota counterparts, the recommendation is 87 regular unleaded. LX supposedly makes about 3 horsepower extra. GX actually makes less power on premium than the Tundra does on regular.
This is a pretty common theme in the GX premium crowd.
For what it's worth, where I am, at Costco, the difference is about $7-$8 per tank.
At most other places in town, the difference is easily $15 or $20 per tank.
Even six bucks a tank adds up though, which is hundreds of dollars per year.
And also, we're at the point now where I'd say most 2nd gen GX owners have bought their vehicles used, for a price that's some fraction of $60k, even new. I paid $30k for mine, and now I'd be lucky to get $20k for it today. One of the many factors in my GX vs 4runner decision was knowing (from research) that the GX could also run regular.
GX guys are split, with most tending to go with premium.
LX guys are split, with most tending to go with regular. Go figure.
Though these days it seems the GX guys are also now trending regular, probably a result of the car getting older/cheaper.
It's pretty settled that both GX and LX will not knock with any 87 octane product or better. I have not come across anyone on the internet or in person who has had knock running regular in a GX or LX (or Tundra or land cruiser for that matter). You may be able to find someone who has or thinks they have, but it seems there are countless owners reporting that they run regular with no issues.
On the other hand, you can find plenty of people with modern fuel injected cars that do knock when lower than recommended octane is used. E.g. for the Acura MDX this is a common issue, and I know first hand that my wife's MDX in particular will knock if you put less than premium in the tank.
For the GX, the only real arguments open for debate running regular are a perceived lack of performance/fuel economy, or a theoretical gradual wear issue and possible future repair bill. There are compelling arguments on both sides, but to-date there have been no reported incidents from running regular, and the 2nd gen GX has been running around for a decade now. Also FWIW nobody has put this to the test on the dyno either. So again, performance and wear are up for debate but nebulous at best.
Manufacturers tend to "recommend" 91 octane for their luxury or sporty lines because that is what the customers expect and it differentiates the vehicle from the "lesser" versions. A prime example is the Toyota Land Cruiser and the Lexus LX. The LC requires 87 while the LX recommends 91. The LX makes a whopping 2 or 3 extra hp from the 91 octane
For what it's worth, where I am, at Costco, the difference is about $7-$8 per tank.
At most other places in town, the difference is easily $15 or $20 per tank.
Even six bucks a tank adds up though, which is hundreds of dollars per year.
And also, we're at the point now where I'd say most 2nd gen GX owners have bought their vehicles used, for a price that's some fraction of $60k, even new. I paid $30k for mine, and now I'd be lucky to get $20k for it today. One of the many factors in my GX vs 4runner decision was knowing (from research) that the GX could also run regular.
The following 4 users liked this post by Craigyyy:
12-02-19, 01:20 PM
#392
Advanced
New 2019 GX 460 owner. Been using 87 octane and noticed GX is kinda sluggish. Don't really want to pay 30 cents more per gallon but asking if it makes any difference to run 91? The owners manual and filler cap says to use Premium but haven't. Why does it say that? Please advise if using 87 makes any difference?
12-02-19, 01:21 PM
#393
Pole Position
Awesome ... let's get a thread going on "Which Combination of These Three Variables is Best?" ... Conventional vs Synthetic Oil, Octane Rating and Percent Ethanol ... 
... and we can add Oil Change Interval for even more fun 
Seriously ... automakers assume E10 (10% Ethanol) for gas mileage purposes given it is pretty much standard nationwide and has 96.7% the energy value of 100% pure gasoline, so per the EPA ... gas mileage will be reduced by approximately three percent when compared to pure gasoline. Whatever octane rating is posted on the pump IS the octane level being pumped whether E10, E15 or pure gasoline. Here is a great resource to find pure gas in your area ...
https://www.pure-gas.org/
... and we can add Oil Change Interval for even more fun Seriously ... automakers assume E10 (10% Ethanol) for gas mileage purposes given it is pretty much standard nationwide and has 96.7% the energy value of 100% pure gasoline, so per the EPA ... gas mileage will be reduced by approximately three percent when compared to pure gasoline. Whatever octane rating is posted on the pump IS the octane level being pumped whether E10, E15 or pure gasoline. Here is a great resource to find pure gas in your area ...
https://www.pure-gas.org/
Last edited by ASE; 12-02-19 at 05:26 PM.
The following users liked this post:
Craigyyy (12-03-19)
12-02-19, 09:37 PM
#394
Rather than getting into a virtual fistfight over gas, I'd offer the following:
On your daily commute, keep track of mileage/mpg/price etc for two tanks of gas using whatever you generally fill up with.
Fill your car with the other stuff, run that tank pretty much down
Run two more tanks of that stuff and track the same info as before. Post the results here for the group. That will enable the group to do a cost/benefit analysis.
On your daily commute, keep track of mileage/mpg/price etc for two tanks of gas using whatever you generally fill up with.
Fill your car with the other stuff, run that tank pretty much down
Run two more tanks of that stuff and track the same info as before. Post the results here for the group. That will enable the group to do a cost/benefit analysis.
12-03-19, 06:11 AM
#395
Lead Lap
Though it's a little different, I have the GS460, and I, as well as the previous owner, have only ever used premium in it. The one time my friend borrowed the car and put 87 in, I could hear some very mild pinging when accelerating up the hill, but nothing too terrible. Definitely would only run premium if I were you, however. If you can't, like you mentioned, then just toss a bottle of Techron or Redline SL-1 through the tank every 4-6 months.
12-03-19, 08:47 AM
#396
Though it's a little different, I have the GS460, and I, as well as the previous owner, have only ever used premium in it. The one time my friend borrowed the car and put 87 in, I could hear some very mild pinging when accelerating up the hill, but nothing too terrible. Definitely would only run premium if I were you, however. If you can't, like you mentioned, then just toss a bottle of Techron or Redline SL-1 through the tank every 4-6 months.
12-03-19, 09:09 AM
#397
Pole Position
The bottom line ... the knock sensor will retard the ignition timing to prevent engine damage from pre-ignition when running low(er) octane fuel. So if you want maximum power, run high(er) octane for optimum ignition timing. If you don't care, run whatever you want ... the knock sensor will adjust engine timing to compensate. Yes, with low(er) octane there is the danger that knock sensor compensation is not instantaneous under various throttle and load conditions, but does this result in the engine experiencing a higher level of stress given the engine DOES experience detonation prior to the knock sensor responding ? ... this can be argued all day long.
The following users liked this post:
Juiceboxx (12-03-19)
The following users liked this post:
cb1111 (12-03-19)
04-16-20, 12:47 PM
#401
Premium 93 octane Gas at $1.41 per gallon???
Just purchased 93 octane gas for new 2019 GX 460 at an Indian reservation and saved $15 ($1.41 per gallon) on tank fill up vs. 93 octane ($2.57per gallon) at local Buffalo, NY filling station. My question is how reliable are the octane ratings at Indian reservations with out our government certifying the quality and octane rating stated on the gas pump. I've never had problem with using reservation regular 87 octane on other vehicles. Was wondering if any GX 460 drivers have experienced problems with gas purchased at Indian reservations where the gas is not certified and taxed by federal and state authorities.
09-15-20, 05:17 AM
#402
SO when I read the owners manual it says that during testing Lexus used 96 octane, but they recommend 91 at a minimum, does that mean we should try and find the highest octane rating possible or really anything over 91 will do the trick?
09-15-20, 06:40 AM
#404
The manual says 91(Research Octane Number 96) or higher. Using gas with an octane rating above what the ECU is programmed for does not provide any added advantage TMK.