Premium fuel really needed?
08-10-19, 05:16 AM
#196
Lexus Fanatic
Sorry if this has been covered before, and I did do a search.
I'm looking for one of these and know the gas mileage is bad.
Its V8 is identical to the Tundra's 5.7 which calls for regular. There are zero differences; the compression ratios are identical.
I don't mind driving a gas guzzler but I really don't want to waste $12-15 bucks a tank on high octane fuel if I don't need to.
Does anyone here run regular? I wonder what the service techs at the dealer would tell me. Or the Toyota dealer.
I'm looking for one of these and know the gas mileage is bad.
Its V8 is identical to the Tundra's 5.7 which calls for regular. There are zero differences; the compression ratios are identical.
I don't mind driving a gas guzzler but I really don't want to waste $12-15 bucks a tank on high octane fuel if I don't need to.
Does anyone here run regular? I wonder what the service techs at the dealer would tell me. Or the Toyota dealer.
I only have personal experience with the 4.7 engines. Our past LX470 required premium fuel whereas our 4Runner with the identical 4.7 (Tahara built) V8 stated regular fuel is fine, but for optimal performance, use premium. We have two failed cats on our 4.7 4Runner at just 110K.
Its V8 is identical to the Tundra's 5.7 which calls for regular. There are zero differences; the compression ratios are identical.
I can't imagine the Toyota engineers made a mistake and put the premium fuel disclaimer in the manual.
Here is an interesting POV from IH8MUD:
Thanks. Like any good engineering discussion, talking through details and disagreements fosters understanding. We may not always agree, which is fine, as any problem has multiple solutions. Money is just as important as a factor as engine wear. Only the individual can decide in the end. I believe that money vs wear is the relevant trade space. Rather than money vs. power or money vs mpg, though you do get the benefit of both of those.
In regards to your point on octane tolerance. I don't disagree. Any good design would mitigate the risks of lower octane. But there is a difference in short term risk, vs. prolonged usage outside of the design envelope. It is exactly the knock sensors that would be in play to mitigate the risk.
Consider this. The only way the ECU knows to back down timing, is to witness knock. For some duration, at which point it seeks its nominal maps, only to experience knock again. Rinse and repeat. Over a lifetime, how many knock events is that? Compared to a tuned for 87 octane calibration, that never tries to overstep that threshold, resulting in far less knock events.
Is 91 octane always 91 octane? I agree, probably not (it's closer than you think, I would know instantly in my Porsche turbo). But the tolerance will be around 91. Let's say 91 +/- 4 points. Versus 87 +/- 4 points. All of a sudden, you guys using a bad batch of 87 in your LX570, are really running 83 octane. Do you still think that's safe? Mix in other variable, such a 100+ degree temps, 35" tires, 1500lbs of gear, on a 7% grade. Safety margins start disappearing.
87 is 4 points from required 91 octane. 4 points from 87 is... Would an LC owner be willing to put 83 octane **** grade in their vehicle? Even the LC guys know better than that!
Different parts of the world use different calibrations for their fuel quality. Japan is known to have among the highest octane gasoline in the world. Same ECU, same everything. Different JDM calibration than our USDM calibration. The tri-state CA/NV/AZ gets lower **** grade 91 along with tighter smog regulations. There's such a thing as CA only calibration. Yet we have a hard time understanding that the LX570 may get it's own calibration?
Last edited by Toys4RJill; 08-10-19 at 06:08 AM.
08-10-19, 05:28 PM
#197
Lexus Champion
And no, I won't be using it just to get groceries. I'm buying it for the solidity, reliability, the luxury, and the capability to get through any blizzard on my regular trips to upstate New York to see inlaws. It can get bad fast when you're in bmfk Ohio or Penn and bad winter weather hits.
I will also be off-roading the hell out of it, as long as I won't damage the paint. There are tons of places to go mudding/off roading around here.
And yes, it's a waste of money using premium, I'm pretty sure. Lexus wouldn't sell a vehicle made for regular gas, it would throw off the "premium brand" pretense. The motor is completely identical.
Last edited by AJT123; 08-10-19 at 05:34 PM.
08-10-19, 05:33 PM
#198
Lexus Champion
This is a long debate.
I only have personal experience with the 4.7 engines. Our past LX470 required premium fuel whereas our 4Runner with the identical 4.7 (Tahara built) V8 stated regular fuel is fine, but for optimal performance, use premium. We have two failed cats on our 4.7 4Runner at just 110K.
The engine might be the same, but the exhaust system and 4WD are a bit different. The weights are different as well. The LX is at the very top of end of weight and put the most stress on the 5.7 for sure. I do not think the Toyota 5.7 is rated for SAE J2807spec numbers. For example, my 04 4Runner was not rated at the SAE spec, while the 06 4Runner was. So the 381hp for all Toyota models is a bit misleading IMO.
I can't imagine the Toyota engineers made a mistake and put the premium fuel disclaimer in the manual.
Here is an interesting POV from IH8MUD:
I only have personal experience with the 4.7 engines. Our past LX470 required premium fuel whereas our 4Runner with the identical 4.7 (Tahara built) V8 stated regular fuel is fine, but for optimal performance, use premium. We have two failed cats on our 4.7 4Runner at just 110K.
The engine might be the same, but the exhaust system and 4WD are a bit different. The weights are different as well. The LX is at the very top of end of weight and put the most stress on the 5.7 for sure. I do not think the Toyota 5.7 is rated for SAE J2807spec numbers. For example, my 04 4Runner was not rated at the SAE spec, while the 06 4Runner was. So the 381hp for all Toyota models is a bit misleading IMO.
I can't imagine the Toyota engineers made a mistake and put the premium fuel disclaimer in the manual.
Here is an interesting POV from IH8MUD:
I don't see how the exhaust and 4X4 would have anything to do with it.
08-10-19, 08:56 PM
#199
Pole Position
Thanks, Jill, for all of this. Those are fair points, but even at 6k lbs plus I don't think the V8 is overtaxed, at all. The last gen LX was, but not this one. I've seen 0-60 times as fast as 6.5 seconds for the 570, and people on here have told me that with regular driving the truck just loafs during regular driving not working/revving hard bc 90% of torque is available at 2200 RPM.
I don't see how the exhaust and 4X4 would have anything to do with it.
I don't see how the exhaust and 4X4 would have anything to do with it.
I've been on mud for 10 years and I've NEVER heard of an engine failure due to using regular gas where premium is recommended.
08-10-19, 10:51 PM
#200
Lexus Fanatic
Thanks, Jill, for all of this. Those are fair points, but even at 6k lbs plus I don't think the V8 is overtaxed, at all. The last gen LX was, but not this one. I've seen 0-60 times as fast as 6.5 seconds for the 570, and people on here have told me that with regular driving the truck just loafs during regular driving not working/revving hard bc 90% of torque is available at 2200 RPM.
I don't see how the exhaust and 4X4 would have anything to do with it.
I don't see how the exhaust and 4X4 would have anything to do with it.
08-11-19, 08:38 AM
#201
Actually it's a $90,000 vehicle.
And no, I won't be using it just to get groceries. I'm buying it for the solidity, reliability, the luxury, and the capability to get through any blizzard on my regular trips to upstate New York to see inlaws. It can get bad fast when you're in bmfk Ohio or Penn and bad winter weather hits.
I will also be off-roading the hell out of it, as long as I won't damage the paint. There are tons of places to go mudding/off roading around here.
And yes, it's a waste of money using premium, I'm pretty sure. Lexus wouldn't sell a vehicle made for regular gas, it would throw off the "premium brand" pretense. The motor is completely identical.
And no, I won't be using it just to get groceries. I'm buying it for the solidity, reliability, the luxury, and the capability to get through any blizzard on my regular trips to upstate New York to see inlaws. It can get bad fast when you're in bmfk Ohio or Penn and bad winter weather hits.
I will also be off-roading the hell out of it, as long as I won't damage the paint. There are tons of places to go mudding/off roading around here.
And yes, it's a waste of money using premium, I'm pretty sure. Lexus wouldn't sell a vehicle made for regular gas, it would throw off the "premium brand" pretense. The motor is completely identical.
08-11-19, 08:49 AM
#202
Lead Lap
As they say to each his/her own. If you own a vehicle in warranty, then yes, KISS and just put in premium. However if your buying used with or without warranty, or you really dont mind the going back and fourth to prove that the gas tier caused them to deny your warranty claim, then by all means.
This thread topic pops up in every forum, and both sides bring out expert witnesses to the fact, but at the end of the day, do whats best for you, and deal with the benefits or consequences lol.
This thread topic pops up in every forum, and both sides bring out expert witnesses to the fact, but at the end of the day, do whats best for you, and deal with the benefits or consequences lol.
08-11-19, 01:16 PM
#203
As they say to each his/her own. If you own a vehicle in warranty, then yes, KISS and just put in premium. However if your buying used with or without warranty, or you really dont mind the going back and fourth to prove that the gas tier caused them to deny your warranty claim, then by all means.
This thread topic pops up in every forum, and both sides bring out expert witnesses to the fact, but at the end of the day, do whats best for you, and deal with the benefits or consequences lol.
This thread topic pops up in every forum, and both sides bring out expert witnesses to the fact, but at the end of the day, do whats best for you, and deal with the benefits or consequences lol.
I'd opine that the majority of the posters on all of the forums that this comes up in pull up to the "Regular" pump when it comes to their wallets.
That doesn't mean that there isn't a place for premium gas and there are plenty of cars that require (or run better) on premium - I don't think this is one of them.
08-12-19, 11:52 AM
#204
To add to some fuel to the fire... 
I have been running nothing but regular fuel in my 2013 Tundra since I bought it new, it now has 95k miles and still runs like a top.
Carry on!
I have been running nothing but regular fuel in my 2013 Tundra since I bought it new, it now has 95k miles and still runs like a top.
Carry on!
08-12-19, 01:01 PM
#205
Lexus Champion
That's so true - with one minor exception. Here, you have the comparison to a nearly identical vehicle/engine that the same manufacturer says requires regular.
I'd opine that the majority of the posters on all of the forums that this comes up in pull up to the "Regular" pump when it comes to their wallets.
That doesn't mean that there isn't a place for premium gas and there are plenty of cars that require (or run better) on premium - I don't think this is one of them.
I'd opine that the majority of the posters on all of the forums that this comes up in pull up to the "Regular" pump when it comes to their wallets.
That doesn't mean that there isn't a place for premium gas and there are plenty of cars that require (or run better) on premium - I don't think this is one of them.
08-12-19, 04:49 PM
#206
08-12-19, 05:08 PM
#207
Lexus Fanatic
You can’t always hear engine knock. And the idea that Toyota engineers are wrong to require it or the idea that it is a marketing thing is just absurd
Last edited by Toys4RJill; 08-12-19 at 05:25 PM.
08-12-19, 05:13 PM
#208
Pole Position
I have yet to hear knock on neither the '01 LX nor the '13 200 series. Knock sensors feel the beginnings of knock and retard timing accordingly.
08-12-19, 05:25 PM
#209
Lexus Fanatic
08-12-19, 05:33 PM
#210
Lexus Champion
For just wafting around which is what the LS430 does best, you can't tell anything.
That said, I put premium in it. It gets good gas mileage for what it is.
I'm not putting premium in unnecessarily in a vehicle that gets 12MPG, though, where the exact same identical motor, literally, that goes into Tundra and LC takes regular.