View Poll Results: Fuel Type?
Regular
26
12.32%
Midgrade
25
11.85%
Premium
160
75.83%
Voters: 211. You may not vote on this poll
The Mother of all LS430 Fuel Threads: Regular, Midgrade, or Premium? (merged)
#242
Moderator
The theoretical expectation should be that lower grade fuel (ie regular versus premium) will result in some what lower mpg, performance and HP. It is fairly common currently for gas distributor to up ethanol content to boost octane in premium gas. Ethanol has less energy in it so you can end up with lower mpg with premium these days.
I can't recall ever seeing any objective study or set of measurements being published to verify or confirm performance and mpg results of different fuel usage in the LS. We have had anecdotal results via periodic posting by folks saying they use regular and get same, better, worse performance, etc - not much in the way of confirm-able usable data.
If I was on a budget and driving lots of miles I'd likely use regular in the LS unless I was driving mountains, high temp, or carrying heavy loads in the car where high octane premium would protect against load/temp induced knock.
Last edited by Jabberwock; 12-23-14 at 09:04 PM.
#243
Retired
iTrader: (32)
edit: and the difference was in reference to the detonation..but the performance aspect is effected also.
Agree - the ECU on the LS can detect how the engine is running with a given octane/grade of fuel and will make adjustments to avoid pre-ignition and to run as well as possible with a given fuel grade.
The theoretical expectation should be that lower grade fuel (ie regular versus premium) will result in some what lower mpg, performance and HP. It is fairly common currently for gas distributor to up ethanol content to boost octane in premium gas. Ethanol has less energy in it so you can end up with lower mpg with premium these days.
I can't recall ever seeing any objective study or set of measurements being published to verify or confirm performance and mpg results of different fuel usage in the LS. We have had anecdotal results via periodic posting by folks saying they use regular and get same, better, worse performance, etc - not much in the way of confirm-able usable data.
If I was on a budget and driving lots of miles I'd likely use regular in the LS unless I was driving mountains, high temp, or carrying heavy loads in the car where high octane premium would protect against load/temp induced knock.
The theoretical expectation should be that lower grade fuel (ie regular versus premium) will result in some what lower mpg, performance and HP. It is fairly common currently for gas distributor to up ethanol content to boost octane in premium gas. Ethanol has less energy in it so you can end up with lower mpg with premium these days.
I can't recall ever seeing any objective study or set of measurements being published to verify or confirm performance and mpg results of different fuel usage in the LS. We have had anecdotal results via periodic posting by folks saying they use regular and get same, better, worse performance, etc - not much in the way of confirm-able usable data.
If I was on a budget and driving lots of miles I'd likely use regular in the LS unless I was driving mountains, high temp, or carrying heavy loads in the car where high octane premium would protect against load/temp induced knock.
Last edited by LiCelsior; 12-24-14 at 11:09 AM.
#244
I do feel a difference between 87/93. These cars were specd for 93 and that is what you should use. Mid grade may be OK but I know a Gas station owner and he told me that midgrade is not sold anywhere near 87 or 93 and can get stale in the stations tanks. I also do not think you should mess with any vehicles fuel system... If it calls for 93, then use it.
#245
I can't tell you if there's a difference between 87 and 93 because I've always used 87 in my 03 since I bought it brand new. The only time I ever put 93 in is if I happen to be driving over a mountain pass in the summer or spend time in a place like Phoenix AZ in the summer. If you don't spend a lot of time with the pedal to the metal or quarter-miling then it's not one iota of an issue. My car returns about 26 MPG on the open highway using 87, cruising about 70-75MPH.
#246
XJSfan - I have seen the statement several times that the LS430 requires 93 octane, but can't figure out where that comes from (perhaps non-US owner's manuals). I am aware of the different countries' use of different standards for describing octane ratings. I have attached the page from the 2005 LS430 OM specifying the grade required in the US (91). Do you have a diferent source? Thanks.
#247
XJSfan - I have seen the statement several times that the LS430 requires 93 octane, but can't figure out where that comes from (perhaps non-US owner's manuals). I am aware of the different countries' use of different standards for describing octane ratings. I have attached the page from the 2005 LS430 OM specifying the grade required in the US (91). Do you have a diferent source? Thanks.
#248
Lexus Fanatic
iTrader: (1)
The LS430 does take advantage of higher octane fuels. It's a high compression engine. Don't forget that ethanol lowers the octane rating. You are really not getting 91 or our premium 93 on this side of town. The best mileage I see is when I run an octane boost or something like the Lucas fuel product. As high was 30 consistently mpg on the highway. For road trips it is well worth it. As much as 5 more mpg over 18 gallons is a lot. Have a heavy right foot and can't slow down a little? Don't bother expecting better mileage. 1700 - 2000 rpms is the sweet spot.
Here is a shot of pretty good mileage I got the other evening on standard 93. This was the average across 35 miles.
Here is a shot of pretty good mileage I got the other evening on standard 93. This was the average across 35 miles.
Last edited by Lavrishevo; 12-24-14 at 04:58 PM.
#249
Moderator
Gasoline octane rating is a measure of the resistance of gasoline and other fuels to detonation (engine knocking) in spark-ignition internal combustion engines. It is so named because a fuel composed of 100% iso-octane has an octane rating of 100. Fuels which are less resistant to detonation than this standard are said to have an octane rating lower than 100, fuels that are more resistant than the standard to detonation have octane ratings greater than 100.
Since ethanol is less explosive and more resistant to detonation than iso-octane, it has an octane rating greater than 100. Ethanol octane rating is nominally 113. Mixing it will gasoline with a lower octane rating will boost the rating.
Since ethanol is less explosive and more resistant to detonation than iso-octane, it has an octane rating greater than 100. Ethanol octane rating is nominally 113. Mixing it will gasoline with a lower octane rating will boost the rating.
#250
XJSfan - I have seen the statement several times that the LS430 requires 93 octane, but can't figure out where that comes from (perhaps non-US owner's manuals). I am aware of the different countries' use of different standards for describing octane ratings. I have attached the page from the 2005 LS430 OM specifying the grade required in the US (91). Do you have a diferent source? Thanks.
#251
Lexus Champion
#252
Lexus Fanatic
iTrader: (1)
You are right. I was misinformed in regards to the octane. Ethanol does produce 33% less energy vs pure gasoline which is where the reduced mileage comes from.
To name a few disadvantages of ethanol gasoline, it has lower BTU content than pure gasoline, which means less performance and lower fuel economy. Ethanol absorbs water and carries that water throughout the fuel system and engine; steel and iron gas tanks are prone to rust from water. Ethanol softens and cracks rubber, plastic, and fiberglass parts; engines used for marine applications are most vulnerable to deterioration. Ethanol causes petroleum gasoline to turn to varnish more quickly, meaning less shelf life. Old ethanol gasoline clogs carburetor jets, fuel injectors, fuel injection distributors, fuel pumps, and fuel filters; once varnished, it also sticks to intake valves and ruins the engine.
#253
Pole Position
Over 500K miles over 20 years on 4 different LS's including 250K on my '01 running 87 octane. 25 mpg +/- highway @ 75+ mph. No gas-related issue whatsoever. Starts immediately in the morning at 15 below zero.
MPG is a function of so many contributing variables other than simply the "stated" octane rating (actual octane varies), including weather conditions (wind, temperature (cold better), humidity, tires including rolling resistance of tire rubber composition, tread configuration and tire pressure, wheel alignment, engine performance characteristics (fuel - air mix), spark plugs, mass air flow sensor, fuel injectors performance, choice of oil type/grade, combined weight of wheels/tires, and obviously whether the A/C compressor is "on" or "off." Having just replaced both of the oil control valve solenoids at 251K miles, even that has improved my highway MPG by 1 mpg due to their effect on more efficient variable engine timing. Oh, and my 5-speed '01 with over 250K miles gets better overall MPG than my 6-speed '06 with 60K+ miles. There is less internal friction in the higher mileage engine.
Definitely run premium.
MPG is a function of so many contributing variables other than simply the "stated" octane rating (actual octane varies), including weather conditions (wind, temperature (cold better), humidity, tires including rolling resistance of tire rubber composition, tread configuration and tire pressure, wheel alignment, engine performance characteristics (fuel - air mix), spark plugs, mass air flow sensor, fuel injectors performance, choice of oil type/grade, combined weight of wheels/tires, and obviously whether the A/C compressor is "on" or "off." Having just replaced both of the oil control valve solenoids at 251K miles, even that has improved my highway MPG by 1 mpg due to their effect on more efficient variable engine timing. Oh, and my 5-speed '01 with over 250K miles gets better overall MPG than my 6-speed '06 with 60K+ miles. There is less internal friction in the higher mileage engine.
Definitely run premium.
#254
In my 2006 Lexus manual it says premium unleaded gasoline with an octane rating of 91 or higher for optimum engine performance. In my state it is 93 octane and whatever you want to use is up to you...
Last edited by XJSFan; 12-26-14 at 11:41 AM.