Use the lowest octane that doesn’t cause pinging or knocking. The ONLY thing premium about gas is the steability at higher pressures…
93 octane doesn’t self-ignite as easily, and in higher compression engines this matters…
Is it worth it?
I get a bump in mpg and power when using premium so I pay up.
I used to regularly swap between the two, and swap computers when I did so, so I’d regularly be burning a mix or the rest of the premium on the stock tune, no difference to mpg. (Untuned)
Depends a lot on the engine or even just the timing.
My 2023 can ramp up and down power by analysing various signals.
I had an old sports car that could detect knock and pull timing but that was about it. Waiting until it knocks isn’t super healthy.
I have an old truck that I could set timing using high octane and get some better efficiency out of it, but I’d rather it be able to run on a mix of sewer runoff and coyote piss so it’s timing is pretty forgiving.
Isn’t it more about long term engine health than any immediate mpg gains?
With a sticker like that, probably. I have a car that requires premium or else it can ping (predetonate) with the right conditions and risk “ring land” damage. My other car says “91+ recommended”. It gets better fuel economy on premium, but the cost of premium is higher than the mpg benefit, even before post-covid premium price gouging that never let up.
No. Octane isn’t better or worse for your engine. It’s about compatibility.
It’s required to prevent detonation (fuel igniting in the cylinder before its supposed to due to pressure) which will damage your engine.
Maybe some cars can adjust their tune based on the octane level, but for those that can’t it’s definitely worth it.
mine specifically says not to use anything but 87. and also to stay away from ethanol-free fuels. so, yes, they can and do tune the engines for a specific fuel mixture.
What kind of car?
My old Murano*could benefit from premium. But I’d get maybe 1 more mpg and maybe 5-10 more torques. Butt dyno couldn’t even notice it.
Horrified at the thought of a butt dyno
Ford Bronco with the 2.7 and a ford performance ecu flash.
Right? My previous car was designed to be flexible premium cost roughly the same with mpg boost and the car was more powerful. It’s really not that different I was a poor college kid at the time too.
Now if your car is premium only and you are putting regular in you are just looking to break something.
My understanding was the premium was just more stable, reducing predetonation with higher compression. Unless you are losing mpg or power to predetonation wouldn’t switching make no difference? I ask out of curiosity, I’ll admit I know very little on fuel specifics.
Cars with electronicaly adjustable timing will detect if there is knock caused by pre-detonation/pre-ignition and advance or retard the timing to compensate. So cars that can do both octanes will have the timing more advanced when premium gas is present allowing for more power and efficiency. More timing with lower octane gas will explode earlier than expected causing pre-detonation/pre-ignition.
Engines that have premium requirements usually have higher compression, forced induction (turbo super, charger, ect) or even a more aggressive cam setup that advances timing where variable timing can’t compensate or it doesn’t have variable timing. So they need higher octane in order to ensure the engine isn’t igniting at the wrong time, which over time damages pistons, rings and other components.
Also if your car is not designed for both, you are just throwing money away getting premium if it requires regular. Best case no difference or in the case of my wife’s car would actually cause a check engine light.
VVT isn’t really needed for that though, advancing spark can be enough to avoid knock. Although I’m not sure if an engine like that would receive benefits from premium.
Yes I may be confusing the two here I’ll adjust
VVT does achieve the goal too, if you close the valves later you’ll def. have a reduced compression ratio. That helps avoid premature ignition through compression. (Well, duh…)
But igniting the mixture earlier also helps, probably won’t work for engines that are to high in compression.
And forced induction engines with electronic boost control could lower boost pressure, that would also help avoid knock.
At least that’s my understanding…
Ahhh got it, that makes sense. thanks!
Premium often has a better additive package.
TBH I’m scared to use the cheaper stuff in my fun car, like it’s going to start falling apart even faster if I don’t give it the good stuff.
Use whatever the manufacturer reccommends. If they don’t reccommend premium, you don’t need premium.
Don’t be scared, be knowledgeable.
Eh. I’ve never owned a car that required “premium” fuel but modern engines are completely capable of adjusting ignition timing as necessary. You’ll just make less power.
Is 1991 modern?
No?
Fully agree and admittedly my comment was more for giggles, but car’s not stock; previous owner upgraded turbos and doesn’t know anything about the tune. I don’t know anyone who can tune an obd1 system so after I get the clutch done my next big project is rewiring with a post-1996 electrical system.
Have you looked into a standalone system like Holley or similar? Seems like they make it easy now at least from the YouTube videos I’ve seen 😅
Premium isn’t better, just more resistant to pre-detonation, if your engine doesn’t make pre detonation more likely, you don’t need it.
My 08 turbo Subaru calls for it my 22 turbo Subaru doesn’t. if I put 87 in the 08, it won’t get very far, on the other hand, the 22 is just fine.
im sorta curious about these things and e85. One thing I noticed is it has higher octane than regular.
Higher octane without an engine that can take advantage of it will just lead to poor mileage. In my case, I can increase the boost on the turbo and make considerably more power out of the same parts, but you’d be more limited when it comes to a naturally aspirated engine. There is more to worry about and it’s not that simple but E85 has a huge scene within the tuning community.
