Premium gas, or?
 

Hi folks,

Does the FR-S/BRZ HAVE to run on premium gas, or could it run on regular/mid and still function efficiently? Would it hurt the engine to run mid grade or regular? Would Scion advertise Premium as getting the most performance or would it run the risk of damaging something if anything else is used?

Thanks!

Says use premium.

In all those cases I do believe it is safe to use the lesser gas, but it results in less power and possibly less efficiency which both offset the savings. So you'd wind up spending the same amount overall, but with less power.

Premium gas is required. In an emergency you can fill it up with less, and the car will pull timing, but the car will run like crap.

Premium gas is only 20 cents more per gallon than regular. Is it really worth potentially harming your engine in car that you just paid nearly 30G's for to save twenty cents a gallon?

Plus this car has very high compression, you are risking knock and pinging by running less than premium, and that is bad, mmkay?

Many threads on this one :search:

It still never seizes to amaze me how people are ready to pay $25k+ for a car and are willing to be cheap on gas.

Not an expert on engines and fuels but I am guessing if it's optimized to run on premium, anything else would give you shitty results and might hurt your engine.

They win nothing by advertising it as premium as they don't get $ from you whether you use premium or regular. If anything, they might lose some potential customers by saying you need premium. Point is, if they are saying you need it, you do. It will run on regular but do you want to put your car through that?

This was a long way of saying, if you are gonna buy a brand new car for over $25k, don't be a cheap a** when it comes to filling it up. :bonk:

I may be wrong but I think cars nowadays have technology to detect the use of lesser gas and the engine performs accordingly, so yes you get lesser performance but I do not believe you can damage or hurt you engine if you went with lesser gas for a few weeks or something. I would of course never do that and would always buy what the manufacturers suggests but its not the end of the world if you accidentally fill up on lesser gas once or twice.

Edit: I was wrong, so ignore everything I said. lol

If you can't afford the 20 cents extra you shouldn't even dream of buying this car.

You're talking about 2 bucks or so whenever you fill up, does that REALLY matter?

You're wrong, it actually can damage your engine.

You can indeed damage your engine if you run regular. Due to the high compression, it needs the 91 (minimum) octane to operate normally. If you put regular and then go into a heavy load situation, your engine will start to knock. It will pull timing but at the same time is also trying to meet the required torque demand (pedal position) and will start a nasty cycle of retard and advancing. Knock destroys engines if it happens far too often over a period of time or too much at once. You want to be cheap? Start by not paying 25k + on a car like this.

In short, dont buy this car if you want to run regular. Your wasting money.

if you calculate the cost of premium, it is an aprox an extra $5 dollars, that is a value meal

Just to clear things up, I have no objection to buying premium gas for the FR-S. A buddy asked me if I knew anything about it and if it was designed to utilize the lesser but perform the best with the high test, but I had no idea so I thought you guys might know more about it.

don't cheap out!

I think out would be okay at lower rpm, but at higher rpm you might cause detonation. With the frs why would you stay at low rpm?

Even though you've already been corrected, there are indeed safeguards built into the car, but it's not meant to be an option to use regularly or even sparingly. The ECU will detect it once the engine starts acting up due to the lower octane fuel, and to prevent any further knocking or stuff like that, it will retard timing, which will allow the engine to run without any huge problems (though of course you will lose some power), but it's meant for the event of premium fuel not being available, as opposed to refusing to use it from that point onward.

Some people do tune their cars to utilize lower octane fuel in a safe manner, but again, it's useless to go through that hassle to save 20 cents per gallon at the cost of a certain amount of performance. But some cars nowadays will adjust as intended by the manufacturer. I know one of the Hyundais adjusts its hp and torque depending on the octane used, but in those cases, the "normal" octane to use is 87 while getting more out of a higher octane when used, not the other way around.

12.5 compression ratio. Enough said.

Just a note, higher elevations generally have lower octane levels, around where I live, 91 is the highest, some places only carry 89. This is not an issue as detonation becomes less of a concern the higher the altitude due to less dense air (so I'm told).

At sea level, I'd always use 93. Up here I'm stuck with 91, and unless I can't get it out of town somewhere, 89 will never be used. My Hemi asks for 91, and there is a noticeable difference in performance with 89 or 87 octane, though I do run 87 from time to time with no adverse effects.

When I used to travel a lot, my '01 Celica was noticeably more peppy with a lower grade of gas at sea level, it's always good to know those cross country trips will usually end in a better performing car for a week or two. ;)

Unfortunately, you can't really buy 93 in California easily. Time for Torco?

you want to put 91 on your FRS/BRZ....I know gas prices are tough at the moment...but don't harm the engine with lesser gas...91!! if you don't want a sports car get a hybrid or something that has 40 mpg...just my 2 cents..

I use 91 on my dinosaur, so why should you on your brand new car? Don't be a cheapo ;)

As of tonight I saw prices near me as
$4.49 for 87
$4.59 for 89
$4.69 for 91...

and $4.29 for Diesel #2 (w00t for my tdi at least for now )

13.2 gal tank. Avg fill up, 11-12 gal. 12 x $0.20 = $2.40 or $7.20/month if you fill up three times a month. I suggest you skip a lunch each month if you can't afford that.

Too much risk with unleaded and you are going to have to use more gas just to get your car to move.

I'm fine with skipping lunch to drive this car. 7.20= fast food around hear so and its bad for you anyways.

91 in my area is about 3.79$ a gallon and reg is about 3.49

$4.05 for 93 in the People's Republic of Massachusetts. Man, you guys really get f****d living in Cali!

I wonder what the owners manual states about using 100% gas or the blended gas with 10% ethanol? I know the ethanol blended gas has less energy than 100% gas so you get worse gas mileage with it.

Gas prices near me:

10% ethanol
87- $3.28
89- 3.38
91- 3.52

100% gas
87- 3.54
89- 3.79
91- 3.90

We don't have that option here... Stuck with 10% ethanol blend. Ethanol has more energy, but burns faster as a result.

E85 contains roughly 1/3 less energy than gasoline per gallon.


But when you add the 1/3 more fuel needed to make things equal you get other benefits that make a big difference if you are running a turbo car.

Ahh, my bad. I knew it was something like that, just got it mixed up.

That doesn't really matter much, since cars today sold in the U.S. are tuned from the factory to run on 91 octane, not that higher octane is a bad thing.

That sucks. I guess I shouldn't complain about paying $4.41/gallon for 91 octane this morning in Orange County (though I was expecting it to come back down a bit after this past weekend).

from Wikipedia:

Ethanol contains approx. 34% less energy per unit volume than gasoline, and therefore in theory, burning pure ethanol in a vehicle will result in a 34% reduction in miles per US gallon, given the same fuel economy, compared to burning pure gasoline. Since ethanol has a higher octane rating, the engine can be made more efficient by raising its compression ratio. In fact using a variable turbocharger, the compression ratio can be optimized for the fuel being used, making fuel economy almost constant for any blend.[25][26] For E10 (10% ethanol and 90% gasoline), the effect is small (~3%) when compared to conventional gasoline,[55] and even smaller (1-2%) when compared to oxygenated and reformulated blends.[56] For E85 (85% ethanol), the effect becomes significant. E85 will produce lower mileage than gasoline, and will require more frequent refueling. Actual performance may vary depending on the vehicle. Based on EPA tests for all 2006 E85 models, the average fuel economy for E85 vehicles resulted 25.56% lower than unleaded gasoline.[57] The EPA-rated mileage of current USA flex-fuel vehicles[58] should be considered when making price comparisons, but E85 is a high performance fuel, with an octane rating of about 94-96, and should be compared to premium.[59

yeah have fun with that over in the land of [s]crazy people[/s] California.

Here in Raleigh, NC premium 93 is around $3.89 most places :clap:

Premium at Costco and Sams is $3.68 right now outside of Minneapolis.

It's perfectly fine to run regular, knock sensors are standard now. But since the FA20 is designed for Premium it's going to run less efficient on regular making the end cost the same or negligible.

OP, run the highest grade unleaded 93 AKI octane if you can, you won't regret it.

In some states, only premium grades can be Ethanol free. The Twins' manual(it's like page 272 or something) says 10% Ethanol is perfectly fine, it's even tuned specifically for it, but it says to not run anything beyond that. Disappointing if, like me, you want to run E85 but that's normal for all sporty cars. :iono:

Ethanol has less energy per gallon, so it's more expensive than you would think, but it makes more power. E85 is the bees' knees for hotrods.

BTW, the EPA does not test MPG on any Ethanol content. They calculate the MPG for all cars based on BTU content.

I'm sorry but that's not true. Yes, it does have knock sensors, and it WILL pull timing, but that can only do so much. The engine may still knock under certain driving conditions which will damage it over time. The FA20/4U-GSE requires premium fuel. It's exactly what it sounds like.

I must ask you to prove it then. Nothing that I've seen or read says that a factory ECU cannot compensate enough for regular grade. I have even seen people run regular on "premium only" engines for many years without a problem.

Edit: Since it's common knowledge and you are refuting it. I did make the initial statement so I will add that you can do a quick search for "can you run regular in a premium engine" and find this.
Why use premium gas when regular will do?

I still say run the highest grade available. It's not like it's expensive. :iono:

I can't personally prove it, but reading an article such as this one will provide insight into the difference between "premium recommended" and "premium required."

But on what kinds of cars? Some can deal with it better, especially if they are not highly tuned with pretty high compression ratios or boosted.

A friend of mine who used to work at Enterprise Rent-A-Car said that they never put anything over 87 octane in their cars, but again, it's not as if they have sports cars in their regular inventory. This came up in discussion when he and I rented a Mercedes E350 for a trip. And again, the E350 isn't a slouch, but it doesn't have the most technologically advanced engine on the market.

That list doesn't include the Twins. I'm going to check the manual again since I know it covered this.

Please report back when you've done so.

They made the car to run on premium so use premium. Its not like the genesis coupe where they actually tell you that you can use regular or premium.

This is all I could find in the BRZ manual.

I don't have a copy of the FRS manual ATM.:bonk:

Edit: Looks like premium is required, I couldn't find the FRS manual but I did find one of the press releases saying premium was required. Sorry guys, I thought after reading the entry on fuel 6 times I wouldn't get confused on which grade was required. :(