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)
03-12-12, 08:01 PM
#226
Moderator
91 or 93 octane availability varies by local distributor... I think its almost impossible to find in the Southwest (west of Texas).
03-17-12, 07:13 PM
#229
In a car that doesn't call for 93 octane, you're not livening it up in the least. You're merely depleting your bank account faster and feeling a false sense of a gain that ain't there.
03-17-12, 08:42 PM
#232
Moderator
I tend to agree that it might be possible to feel a difference between 89 and 93, but very unlikely to be any real world difference 91 and 93 octane rating in the US except well known placebo effect. Once the octane is high enough to allow engine timing to advance per specs and stop pre-detonation there is absolutely no enhancement to smoothness or power with higher than necessary octane.
Yes they do run much higher octane gas for race cars but that is because the engines are higher compression and run much hotter so more pre-detonation is required - higher octane level in gas causes it to burn more slowly.
Also note gasoline octane rating formulas are different from country to country so they cannot be compared between countries as they are derived using a different formula.
Yes they do run much higher octane gas for race cars but that is because the engines are higher compression and run much hotter so more pre-detonation is required - higher octane level in gas causes it to burn more slowly.
Also note gasoline octane rating formulas are different from country to country so they cannot be compared between countries as they are derived using a different formula.
Last edited by Jabberwock; 03-17-12 at 08:47 PM.
03-18-12, 07:58 AM
#233
Come on people.... doesn't it feel good to say "fill'er up with ULTRA" at Sunoco for you ultra cruiser? That's like going all pimped out into a club and saying "just give me water..." 
03-18-12, 07:13 PM
#234
My trip from Birmingham to Indy illustrates the difference between 87 and 91 octane. With 87 octane my LS430 downshifted on most upgrades at 70-75 mph. With premium, it stayed in 6 th gears for the entire northbound run.
Regular grade has the same heat content as premium (excluding ethanol blends). Conditions of power draw leads to timing advance. That is the time that knock is sensed, timing is retarded, and the transmission is downshifted.
I routinely use mid grade, top tier gas. But when I anticipate heavy load situations, premium is my choice.
Regular grade has the same heat content as premium (excluding ethanol blends). Conditions of power draw leads to timing advance. That is the time that knock is sensed, timing is retarded, and the transmission is downshifted.
I routinely use mid grade, top tier gas. But when I anticipate heavy load situations, premium is my choice.
03-18-12, 07:37 PM
#235
Now, when you say you felt a big difference and got better mpg switching from 89 to 93, well that would mostly make sense. You went from one octane that was less than what your car needs to run optimally to one that met and exceeded it. So yeah, that counts, though the "felt a big difference" part, no offense, I have to tell you was imagined in all likelihood.
Secondly, my point wasn't that running premium does nothing for your car. My point was if you're running 93, knowing you need 91, and think on the 93 your car is running "peppier", you're imagining it. The extra octane isn't doing anything for you when you go above the recommended octane rating in this case. But I assume you're like me as where I live you can't really even buy 91 usually, the choice is 89 and 93. I usually fill up with 93 and when I get between 2/3 to 1/2 full I may top it off with 89.
12-23-14, 01:53 PM
#236
Instructor
Is Premium fuel manditory?
I don't want to get into a debate about spending a few extra bucks on premium fuel, I'm sure I will do that but on the flip side I was wondering if there are any out there that run mid-grade or low-grade without any issues. I know someone that is only putting low-grade fuel in their Acura TL and they say they've never noticed a difference.
