Rx900

if the gas prices go down to $1.00 per gallon for premium, then we'll talk. But for now, staying Regular 87.

<VENOM>

regular, I have noticed that the winter and summer blends, the premium winter mix feels like regular, so at 1 point when they switched to the winter mix I switched to regular and then when summer came back to premium but I realized the premium was not worth it with higher priced fuel and lower gas mileage, and not to mention the fuel mileage lost on premium now add a winter premium, I was getting 8-10 mpg when driving in the city, hard take offs from light to light so the regular pushed my mpg up to 13-17 city

Im looking for the best most consistent gas for the engine and premium is not it

super_cjc

I use premium simply b/c it’s recommended in the user manual.
I don't know much about cars so I follow whatever the user manual says.

davidc1

I use premium. Will consider regular if/when it gets close to $3/gal.

yaro1

Thats not entirely true about it not damaging the engine. Putting in lower octane can cause engine "knocking" which is a problem. Higher performance engines often are made especially for premium gas. If you went somewhere that offered 76 octane, it COULD possibly damage your engine. So it does matter some.

I have heard of cases on the Corvetteforum a while back when I prowled there where people drove down to some desolate areas where they have really low octane ratings. Some guy got terrible engine trouble using the lower octane (from reputable places like Shell). He needed a new engine since every time he drove it hard the engine would "knock" and the knock sensor would shut the engine off dead col. (but luckily for him, he had enough money to get a 427 cubic inch twin turbo monster instead of getting stock again ).

Whatever you choose is your choice, but I just don't have even a minute to spare worrying about a problem nevermind having to fix one if it arrises. (That is a part of why I bought Lexus...no worries driving). For me, I would rather pay extra for piece of mind even if it means little gain in perforamcne or relaibility.

By the way..... Diesel is more expensive than Premium by me at some places (I own a trucking buisness in the Bronx NYC) so that comparison is far from what I was talking about. Unless you were being sarcastic and I don't appreciate that .

<VENOM>

the regular would not harm the engine in the long run, I've heard that the only difference between the premium and regular is the rate at which it ignites under compression and that regular and premium have the same detergents in them

davidc1

That's correct. There's no more energy in premium gas than in regular. In fact, it's a shame they call them "premium" and "regular." The only difference is octane rating. Higher the octane rating, the lower the tendency for premature ignition. Generally speaking, higher compression engines require higher octane. Diesel engines have very high compression ratios and they burn without a spark plug. My guess is that GX engine is not the "ultra high performance" engine and shoud be fine with regular (especially since they have knock sensors built in). It's not a requirement. But then, it's what Lexus recommends for best performance. I don't recommend using premium when the engine tuned to use regular, in fact you could hurt the engine by using premium if it's built to use regular. But that's not the case here. So I think you could go either way, I just choose to go with the recommendation till it's too expensive to do so. And it's not yet, at least in Jersey.

T_standard

i heard premium in other parts of the country (i'm from north east) doesnt have a 93 rating.. is that true?

(i put in mid grade 89)

bunka

I was not being sarcastic. Your original replay appeared to try to take a position that "somehow" premium is "better" for your truck than regular when in fact, it isn't. This truck will NOT ping with the typical 87 octane (and therefore your arguement about damage occurring using widely available regular is falsely positioned). In my opinion, your analogy about some joker trying to run a TRUE high Performance engine (Corvette) on EXTREME low-grade regular is misleading and 100% NOT germain to this thread. I was saying that using (typical grade) regular (87) does not damage this truck as it was designed for regular. Your arguement would be valid (damage to your engine) ONLY you tried to use something not designed for it (like Diesel or 76 octane "un-regular"). But you are right, we don't really have time to spend bickering about the details and I am not trying to "push anyone's buttons". Since you get fleet rates on fuel, you probably pay less for your premium than we do for our regular so I don't judge you there.

gqarmstron

hey guys i'm enjoying this thread discussion as i am about to purchase a gx this august when my ml lease is up, and the need for premium gas was a down side the way gas prices are going! so i would like to know if i decide to use regular, should i only continue using reg or can i switch between both reg and premium?

DaveGS4

iTrader: (2)

Hey guys lets keep this discussion friendly please .

One thing to note... most Lexus ECUs (I assume the same is true for the GX) 'learn' over time and will automatically retard timing to adjust to the gas and your driving habits. So two scenarios might be happening... 1) you might not hear any pinging because the timing is retarded and you are getting slightly lower performance as a result 2) you might not hear any pinging because there isn't any problem or detonation issue using the lower octane fuel.

I don't know any way to tell which one is really occurs though..

bunka

You can use either. But using premium resulted in worse fuel economy for most of us. This is probably because the GX is "tuned" to make the best use of regular fuel (fuel economy wise). If you want to use Premium (in theory to get better performance while pulling a trailer or other reasons,) you can do so and then switch back anytime to typical (87 octane) regular.

LeslieRC

Since I already owned an `04 SC and put premium gasoline (93 octane) into that car, the first question I asked the dealer when I was considering the purchase of our `04 GX was the correct grade of gasoline to put into the vehicle. We were told that it would be a waste of our money to put 93 octane into the GX and that 89 octane would do fine.

Donger

Put my first tank of regular in this week. Anxious to see if the heat has any effect on the pining and other bad stuff that may happen. Normally I run premium in all my cars during the 110+ degree summers. I notice nothing at this point, but it is only in the mid-90's right now. I'll post back the first time I sit in freeway traffic with the outside temp reading 135 off the pavement and see if there is any difference.

Melting in Phoenix.....

<VENOM>

I've sat in traffic with the temp reading 135, no problem