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Just wanna know if it’s better to fill up with mid grade or premium unleaded gasoline on an Optima 2020 SE LX.
 

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2013 Ebony SXL Turbo: Original Everything @ about 189K with Drag wheels.
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Possibly not any advantage. I've searched and cannot find If this vehicle can adjust its timing based on octane (some vehicles like Acuras can). My bet is it cannot so using fuel with greater than 87 octane yields zero benefits.

Its a GDI engine so as a results of the design they tend to build up carbon behind the valves more than non-GDI engines. I'd use regular and spend the extra money using de-carbonizing agents like the one Kia shops use (and manual recommends) at least once a year or more often.

Anyone else have more insight into this question?
 

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2020 Kia Soul X-Line 2.0 MPI
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These GDI / TGDI engines will stay cleaner using non-ethanol 93 octane. Very few gas stations sell non-ethanol 87 octane here in Michigan these days. I think Shell might be the only one. It's almost impossible to know, because our laws don't mandate gasoline fuel stations put 10% ethanol stickers on pump handles anymore.

My two engines run better on 93 octane, but it's expensive to run. Premium here averages 70 cents per gallon more than 87 octane. So every tankful is roughly $11-12 more out of our wallet.

Let us know if it pays off, running 93 octane exclusively for 150K. That's the only way to find out. I use mid-grade 89 octane in my Hyundai GDI and 87 octane in our Kia MPI.

4-5 times per year I fill my plastic garage gasoline container for things like lawnmowers and snowblowers. These are the only times I use 93 Premium in my vehicles.

Never fill the garage gasoline container first when arriving at the pump. Most hoses hold a half-gallon of fuel. So if you want Premium for your lawnmower, pump your vehicle first with Premium - then pump Premium "last" into your gallon container. That's because 90% of gas purchases are 87 octane or less and that's what's usually in reserve in that long hose.
 

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2013 Ebony SXL Turbo: Original Everything @ about 189K with Drag wheels.
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Found this: Post your Dynamometer results here!

Perhaps these engines do have a timing adjustment for octane (based on knock sensors)!

As Joemsj51 said, try a tankful or two and measure the differences, I may try my next tankful as mobile 93 for grins. Report back what ya' find!
 

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These GDI / TGDI engines will stay cleaner using non-ethanol 93 octane. Very few gas stations sell non-ethanol 87 octane here in Michigan these days. I think Shell might be the only one. It's almost impossible to know, because our laws don't mandate gasoline fuel stations put 10% ethanol stickers on pump handles anymore.

My two engines run better on 93 octane, but it's expensive to run. Premium here averages 70 cents per gallon more than 87 octane. So every tankful is roughly $11-12 more out of our wallet.

Let us know if it pays off, running 93 octane exclusively for 150K. That's the only way to find out. I use mid-grade 89 octane in my Hyundai GDI and 87 octane in our Kia MPI.

4-5 times per year I fill my plastic garage gasoline container for things like lawnmowers and snowblowers. These are the only times I use 93 Premium in my vehicles.

Never fill the garage gasoline container first when arriving at the pump. Most hoses hold a half-gallon of fuel. So if you want Premium for your lawnmower, pump your vehicle first with Premium - then pump Premium "last" into your gallon container. That's because 90% of gas purchases are 87 octane or less and that's what's usually in reserve in that long hose.
Now we've jumped from changing oil every 3,000 miles to using premium fuel and draining the line before filling, another rediculous post.
 

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2012 Black SX Prem. & Tech.
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I just want to understand what facts make people think premium is better.

I am guessing it's because of marketing and advertising. Because usually the people who like premium don't understand gas, and so the marketing and advertising is all they have to cling to, and are happy to spend $1 per gallon extra for the good feelings.

Kind of like when you have no idea how something works, you just hope that paying more is somehow going to be better.

This doesn't apply for those who understand gas and know why their engine will be more prone to detonation.
 

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My 2019 LX (aka FE) with 20,000 miles on it no longer runs well on 87 octane. Seems to "ping" under load. Runs fine on 89 and higher. It's leased with only 12 months left so I'm not overly worried about it but... I figured it's got some carbon issues already. BTW, I'm strongly in the camp of using 87 octane but in this case it seems to make a difference.
 

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Now we've jumped from changing oil every 3,000 miles to using premium fuel and draining the line before filling, another rediculous post.
Nothing ridiculous (correct spelling) about taking care of our vehicles properly.
BTW..... If you need Premium fuel and instead fill your gallon container half-full with 87 octane instead of 93 octane because you were too shallow-minded to realize the hose and line prior to it holds a half-gallon of regular gas, well that's on your lack of brainpower, as what's custom with most of your posts lately.

My best M.O. today is to put the ill-informed like you On Ignore. Bye.
 

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Nothing ridiculous (correct spelling) about taking care of our vehicles properly.
BTW..... If you need Premium fuel and instead fill your gallon container half-full with 87 octane instead of 93 octane because you were too shallow-minded to realize the hose and line prior to it holds a half-gallon of regular gas, well that's on your lack of brainpower, as what's custom with most of your posts lately.

My best M.O. today is to put the ill-informed like you On Ignore. Bye.
Just thought I'd recant by original post as in retrospect, probably too harsh, so let's just say I think his posts are ill advised and not in the best interest of the community.
 

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2013 Ebony SXL Turbo: Original Everything @ about 189K with Drag wheels.
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Nothing to get worked up about. maybe its covid confinement syndrome...haha

If it knocks with 87 as mjbugg07 says and doesn't with 89+, then by all means use it, right?

My buddy who essentially gave me his '13 optima 2.0T with about 187K on it says premium makes no difference in his experience. Thus far, no pinging on regular exxon so I'll stick to that route. My GF's 330ci can make use of either 87 or 93 but that BMW engine adjusts its timing and makes lots more power with 93, woohoo!!!

Reading thru this article, I can see Some of the Theta engines could make use of premium but it does not mention it for all the Theta IIs, which ours is one of:

.

Luck all and stay safe!
 

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According to the American Petroleum Institute the gas-pump hose typically retains about one third of a gallon of fuel, not 1/2 a gallon.
I see my initial post only contains the hose reference. There is more gasoline in storage from the previous pump user. There's gasoline between the underground tank and the hose that's pulled when the previous user begins his squeeze of his pump trigger. So that fuel line between the underground tank and hose also holds fuel. So that brings it to / near the half-gallon mark I mentioned earlier.

That line I just mentioned may even be a bit longer when mid-grade 89 octane is used. Most-all stations these days are modernized and these stations employ two underground tanks (not 3)..... one for 87 octane and one for 93 octane. So in order to blend mid-grade 89 octane, there's a merger line that brings 87 and 93 together to form 89 octane. Its generally done electronically to produce the blend.

So when the next user is ready to pump the 93 octane they ordered, they will get the prior 87 octane (most likely) that's in the hose and line..... roughly a half-gallon.

I'm done here and will not return to this thread. Have any questions..... PM me instead.
 

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The bottom line is that 87 octane is intended for low compression engines. According to most forums I've looked over, "Low Compression" is between 8:1, and 10:1.

The THETA II engine uses a compression ratio of 11.3:1

Based on that alone, most drivers should be using 89 octane fuel...

If you're using the Turbo version, the compression ratio is higher, so 93 octane is a good choice.
 

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2013 Ebony SXL Turbo: Original Everything @ about 189K with Drag wheels.
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I guess the owners manual is Wrong then, it says 87 pump octane (91 research octane) is minimum recommended. I just wish the engine/ecu were smart enough to adjust timing for higher octane fuels like bmw and acura, its really mostly a waste on these gdi 2.0 turbos....in fact zero gain in fuel efficiency for me....
 

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The theta II ADJUSTS timing according to octane. That's why we can use 87 or 93.

The engineers who designed the engine said you'll get about 10 more HP using 93 compared to 87 on a stock engine. So the cost/performance is not good. But if you want the absolute highest output and have money to waste, then you will get slightly better engine output. I'm not sure if you can feel the difference in 10 HP at the engine, after drivetrain losses etc.

I can't recall the exact link to where the engineers talked about the engine, but yes your 2013 SX Turbo will adjust timing to avoid knock using 87, it runs great and saves money.
 

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Yes, I agree on these points you make. The higher prices for premium fuel does not buy any advantages,unless the auto manufacturers have a system to improve MPG with octane changes.
 
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