use regular gas?

[Draco-REX]

Just some point I want to make:

1. There's NO reason to put anything less than premium in your gas tank. The difference in price is maybe $2-$3 per fill-up. If you can't afford $3, skip lunch before you fill up.

2. Yes these cars have knock sensors and timing tables than can be adjusted by the ECU. But please think about this. It's called a KNOCK sensor. It activates when there already IS knock, not when there's a potential for knock. Just because you can't hear it or feel it, it doesn't mean the engine isn't knocking.

[Nevermore]

All I've seen in my area is 91. Don't think I'll be getting 93 anytime soon.

[motofan]

Originally Posted by RYU

Using 87 will not destroy your motor or cause it to knock. The manufacturers suggest 91 because it is tuned to the advertised hp/tq/mpg numbers at that octane rating. The factory knock sensors and O2 sensors will tune down your timing and other factors to run on 87. You may not achieve the full 199.9hp on the FA20 but it will not damage your car.

In other words, lower octane will decrease performance but not be detrimental. Would I run it for the long term? No.

Agreed. almost all modern cars use knock sensors and they consider lower octane grade when they were designed. Using lower grade would not damage the car. But using lower grade means the engine is not ruining at optimum point and you can get lower MPG. I always put in premium~

[RacelineUSA_Matt]

That salesperson is an idiot.

[Obja]

dont be cheap... im ballin on a budget, but i treat my girl right

[NOHOME]

I would like to know more about the specifics of how low(er) octane fuel damages an engine's components. What will be damaged and from what effect?

Engines rarely knock under steady state conditions; it usually takes a transient such as standing on the pedal and asking for things to accelerate. Pretty much all modern engines have knock sensors and will pull timing out of the engine if it is detected. Hence I wont buy knock as a potential source of damage to the pistons.

So lets say you lose 10 hp or same torque figure. Who would notice on their daily commute. Not me.

The only issue I CAN maybe see is temperature increase from running retarded timing. Since it would be caused by unburnt fuel going out the valve, the valve has to live with higher temperatures. But that would involve the timing being drastically retarded all the time. I do not believe this would be applicable to running say 87 octane in a steady state situation.

What am I missing?

As to the ethanol? While it is a political rip-off, I have to assume that any company that can design this car also can anticipate the fueling challenges and has incorporated them into the equation.

[avp1]

This car uses extremely high compression ratio for a production car. Designers alleviated high octane requirements using direct injection. But still there s potential for detonation in the cylinder. Running for several seconds with strong detonation and your engine is gone. That is why computer senses signs of it and tries to adjust ignitiontiming and other parameters. But it it designed to solve only occasional problems, and not to be used constantly.

Japan's manufacturers build cars not only for US, but for other countries too. There is no problem with getting 98 octane gas (= our 93) anywhere in Europe and other places. If you do not like to use high octane gas, get a domestically made truck that will be happy with 87.

You have to pay for 200 HP got from just 2 litres, plain and simple.

[Leonardo]

13.2 gallon tank. I have never put more than 12 in. 12 X $0.20 (avg. increase for premium) = $2.40 per fill up.

100,000 divided 25 avg mpg = 4000 gallons divided by 12 gallon fill = 333.33 X $2.40 = $799.99 Total savings for using regular gas for 100,000 miles. my math could be off some / also the price of gas will flux.

[avp1]

Originally Posted by Leonardo

13.2 gallon tank. I have never put more than 12 in. 12 X $0.20 (avg. increase for premium) = $2.40 per fill up.

100,000 divided 25 avg mpg = 4000 gallons divided by 12 gallon fill = 333.33 X $2.40 = $799.99 Total savings for using regular gas for 100,000 miles. my math could be off some / also the price of gas will flux.

FA20 engine won't survive 100000 miles on regular gas. So add cost of 2-3 new engines in the equation.

[steeloyangster]

To speak on behalf of the sales person/persons who do and or have done this they are obligated to their dealerships to fill up with regular gas. They receive a gas card when the car needs gas from their Sales Manager. They are always instructed to get the lowest/cheapest gas at their designated "Fill Up" station where they are only supposed to put anywhere from 5-10 dollars at most. Things might change once the car is sold, you might be able to convince them for a full tank of Premium gas but that's because the car is sold.

Myself personally, I felt like a shitbag when I took a Corolla XRS out for a drive with a customer and when we stopped to fill up, I saw the gas cap read "PREMIUM ONLY" and I reached for the regular because I know I'd have issues with the gas station clerk and my boss if I didn't.

I remember another time when a customer purchased a use Jetta TDI and when the salesperson went to fill it up since it wasn't just regular gas the card got rejected. He had to call me since he was broke and I had to pay 15 bucks to fill up the car. When I returned with the receipt my sales manager was gritting his teeth and mumbling under his breath about reimbursing me 15 for it.

[GenkiElite]

Most dealerships do this. They just put in the cheap stuff. The larger dealerships have thier own pump with only one fuel type. I used to work at a very large Toyota dealership that did this.

[WingsofWar]

Originally Posted by steeloyangster

To speak on behalf of the sales person/persons who do and or have done this they are obligated to their dealerships to fill up with regular gas. They receive a gas card when the car needs gas from their Sales Manager. They are always instructed to get the lowest/cheapest gas at their designated "Fill Up" station where they are only supposed to put anywhere from 5-10 dollars at most. Things might change once the car is sold, you might be able to convince them for a full tank of Premium gas but that's because the car is sold.

Myself personally, I felt like a shitbag when I took a Corolla XRS out for a drive with a customer and when we stopped to fill up, I saw the gas cap read "PREMIUM ONLY" and I reached for the regular because I know I'd have issues with the gas station clerk and my boss if I didn't.

I remember another time when a customer purchased a use Jetta TDI and when the salesperson went to fill it up since it wasn't just regular gas the card got rejected. He had to call me since he was broke and I had to pay 15 bucks to fill up the car. When I returned with the receipt my sales manager was gritting his teeth and mumbling under his breath about reimbursing me 15 for it.

OUCH! that sucks, i completely understand that its common practice to fill up using the lowest grade fuel. To no fault of the sales reps, its what they are told to do.

But its also unwise if the car in question was a performance car. Would you put 87 octane in a Rx7..or a 458 Italia, maybe, but to ignore the implications could be pretty disastrous. (i wonder if Nissan puts 87 octane in their GT-Rs)

Lets say the FR-S has been running on 87octane for awhile now, the ECU has detected knock, and has adjusted the timing appropriately. But at 12.5:1 compression and retarded timing, EGTs have increased, NoX levels have increased, Allowing o2 sensors to build up quicker, cats to foul quicker, EGRs to foul quicker. Even if the pistons are in no more danger, the combustion environment has changed to a level not suitable for normal wear are tear of engine components. With DI, carbon buildup is becomes worry some also.

I dunno, but if you ask me, i think Scion might need to rethink their policy on certain models they have on stock.

[steeloyangster]

Originally Posted by WingsofWar

OUCH! that sucks, i completely understand that its common practice to fill up using the lowest grade fuel. To no fault of the sales reps, its what they are told to do.

But its also unwise if the car in question was a performance car. Would you put 87 octane in a Rx7..or a 458 Italia, maybe, but to ignore the implications could be pretty disastrous. (i wonder if Nissan puts 87 octane in their GT-Rs)

Lets say the FR-S has been running on 87octane for awhile now, the ECU has detected knock, and has adjusted the timing appropriately. But at 12.5:1 compression and retarded timing, EGTs have increased, NoX levels have increased, Allowing o2 sensors to build up quicker, cats to foul quicker, EGRs to foul quicker. Even if the pistons are in no more danger, the combustion environment has changed to a level not suitable for normal wear are tear of engine components. With DI, carbon buildup is becomes worry some also.

I dunno, but if you ask me, i think Scion might need to rethink their policy on certain models they have on stock.

Yeah, it sucks that this has to happen to cars but it doesn't matter to the dealerships themselves. Cars have a "LOT LIFE" which is typically anywhere from 1 month to 6 months. If the car doesn't move at 6 months, then the dealership has an opportunity to send the car back to the factory. But then there are things called "TRUNK MONEY". Trunk Money is when the factory pays the dealership extra money to keep the car on the lot, anywhere from 500 - 5000 dollars depending on model/trim and other factors. That's why the dealerships are able to sell a car for so cheap in the latter part of the model year cycles.

What I mean by this is that Scion will not change their policies based on 1 model that they have in their lineup. When I worked at Honda, they were much more lenient with the type of gas that they get. They had S2000's and SI's on the lot which "required" high octane because of the high compression engines. But since putting regular octane in their high performance cars saw a huge decrease in performance, they had no choice but to put high octane in their high performance cars. I've driven an S2K with about half a tank of regular gas at my time at that dealership in particular, and I remember when it got close to V-Tech, it honestly would stutter a couple of times before it got there. Very notice-able by car enthusiasts but not the regular Joe-Schmo.

I hate these policies but hopefully only a small amount of regular fuel actually gets into these cars before an owner gets a hold of them.

[Lonewolf]

Originally Posted by NOHOME

I would like to know more about the specifics of how low(er) octane fuel damages an engine's components. What will be damaged and from what effect?

Engines rarely knock under steady state conditions; it usually takes a transient such as standing on the pedal and asking for things to accelerate. Pretty much all modern engines have knock sensors and will pull timing out of the engine if it is detected. Hence I wont buy knock as a potential source of damage to the pistons.

So lets say you lose 10 hp or same torque figure. Who would notice on their daily commute. Not me.

The only issue I CAN maybe see is temperature increase from running retarded timing. Since it would be caused by unburnt fuel going out the valve, the valve has to live with higher temperatures. But that would involve the timing being drastically retarded all the time. I do not believe this would be applicable to running say 87 octane in a steady state situation.

What am I missing?

As to the ethanol? While it is a political rip-off, I have to assume that any company that can design this car also can anticipate the fueling challenges and has incorporated them into the equation.

Considering that people have encountered knock while running 91 in stock form...using 87 is really asking for it, especially with the 12.5 compression ratio.