Unleaded in a car that`s specd for premium.

[aquariuscsm]

My Z is specd for "Premium Unleaded Fuel Only". Last week I accidentally put regular unleaded in it (yeah,I had my head in the clouds!). What`s weird,my car seemed to run smoother and had harder pull and smoother upper rpm acceleration. Seemed to get better gas mileage too. Is premium gas a sales scam?

NOTE-I get occasional "pinging" when I shift really hard and put my foot in it,BUT,that happens whether I use premium or regular unleaded. Is this pinging being caused by the ethanol being put into gas nowadays?

I also read that using regular unleaded in a car that`s specd for premium won`t hurt a thing (Cartalk.com).

What`s everyone`s take on this?

 

[BrownBox88]

To me, using unleaded in a car spec'd for premium makes you press the gas pedal further down to make up for the lost performance of not using premium. I can tell a heck of a difference in my premium spec'd cars. I don't think it'll hurt though since the ecu will retard timing.

 

[dparm]

Never trust the butt dyno.

The car has knock sensors and will do fine on regular, but I wouldn't make a habit of doing this.

Whenever my folks drive to Kanasas City (to see family), they used to run 87 in their Infiniti I30t. For highway driving there was no difference and it saved them some cash on the 1000 mile round trip.

 

[HTSS_TR]

I had been using regular in all my cars that specd for premium. I could not detect any difference in performance/acceleration, even in the S2000 which I redline several times a day.

Yes, it's cheaper and getting better gas mileage to boost.

 

[EricF]

i ran regular in my wife's old 01 eclipse (glad to have gotten rid of that money pit) and it was fine. Ran premium when I went to smog it, then back to regular. gas mileage never changed (was poor anyway) and it didn't even notice.

and yeah, the knock sensors did their job just fine!
Did this for 5 years.

 

[Pablo]

Did it REALLY get better MPG? That would be the only difference we get with 92 vs 88 R+M/2 fuel. Slightly better mpg with 92

"Premium" should only have a bit better resistance to knock, other than that I think the premium has "more power" is a scam for sure, and premium has "better additives for cleanliness" is debatable.

 

[gathermewool]

I've run bad premium in my STI and it was noticeable in the logs, in form of knock. I'd trust some one like me who logs for knock and dynamic advance over any anecdotal evidence any day. Also, I'm going to point out to others the list of fluids you've got in that thing. If you wanted to skimp on any one fluid and still be safe, fuel wouldn't be much choice.

With that said, a non-turbo vehicle that requires premium because of high compression ratio and/or aggressive timing is a whole different beast, so running regular is more within the capability of the ECM to pull timing and prevent damage.

In these instances, and IMO, it's going back and forth between higher and lower octane that increases the risk of damage. In other words, if you want to run regular some of the time, you might as well run it all the time. Otherwise, you run the risk of "putting your foot into it" after just filling up with regular and the ECM having to play catchup the pull timing due to knock.

FYI: The car's ECM may aggressively combat knock by quickly pulling timing, but all it takes is one good knock event to cause damage, be it a spun bearing or the piston ringland.

 

[Scott_Tucker]

Premium fuel is not a scam, it can produce more power. However, there is no reason to sell three grades at the pump. It is just a marketing scam. All cars could be tuned to run on the same octane fuel. My civic is noticeably slower on 87. If you think your car is making more power on 87 either the premium you were using was bad, or you're imagining things.

 

[Trinh]

Originally Posted By: aquariuscsm
My Z is specd for "Premium Unleaded Fuel Only". Last week I accidentally put regular unleaded in it (yeah,I had my head in the clouds!). What`s weird,my car seemed to run smoother and had harder pull and smoother upper rpm acceleration. Seemed to get better gas mileage too. Is premium gas a sales scam?

NOTE-I get occasional "pinging" when I shift really hard and put my foot in it,BUT,that happens whether I use premium or regular unleaded. Is this pinging being caused by the ethanol being put into gas nowadays?

I also read that using regular unleaded in a car that`s specd for premium won`t hurt a thing (Cartalk.com).

What`s everyone`s take on this?

i also have a highly modified 300zx putting down about 500rwhp, do you have a na or a tt?

 

[Trinh]

Originally Posted By: Pablo

"Premium" should only have a bit better resistance to knock,

in forced-induction applications, they have superior resistance to knock.

i know someone who was trying to save some money by running regular in a turbo-ed nissan, and his pistons cracked due to knock.

Originally Posted By: Scott_Tucker
It is just a marketing scam. All cars could be tuned to run on the same octane fuel.

it's not a marketing scam, higher octane is better at suppressing knock, why do you think the big horsepower guys run race fuel, C16 or Q16, etc.? the newest fad, for lack of a better word, is E85. again, this is for forced inductions, if you have a naturally-aspirated platform, you don't really see the benefits.

 

[Trajan]

I did the same thing in the Z4, though on purpose. Less power, less mpg.

Though if the knock sensors died....

 

[tommygunn]

Premium fuel is for higher compression engines and when you're running boost. Regular in a car running either means the ECU has to cripple things a little and retard timing and reduce boost but it should run fine, but I would be wary of potential engine damage as the car will keep trying to push timing and boost up for high octane fuel.

Premium fuel in a car calling for regular fuel is flatout stupid.

 

[aquariuscsm]

Originally Posted By: Trinh
do you have a na or a tt?


I have a completely stock n/a. ONLY mod I`ve ever done was the bronze SPL shifter bushings. Tried a short shifter once,hated it,and went back to the stock shifter.

 

[aquariuscsm]

Originally Posted By: Trinh
it's not a marketing scam, higher octane is better at suppressing knock, why do you think the big horsepower guys run race fuel, C16 or Q16, etc.? the newest fad, for lack of a better word, is E85. again, this is for forced inductions, if you have a naturally-aspirated platform, you don't really see the benefits.

Now I know legit race gas is definitely not a scam,but I really do have to wonder about your typical gas stations. The world is full of marketing scams and ploys to get more of the consumer`s money. So who knows,huh!

Now my car NEVER knocks,it just will ping when I shift hard with my foot in it. Sounds like a very *tinny* tapping sound from the valvetrain. BUT,it does this on premium too,regardless of the brand of gas.

Is it the ethanol causing the pinging? Mr car NEVER pinged before that [censored] ethanol gas came on the market.

 

[Trinh]

Originally Posted By: aquariuscsm

Now my car NEVER knocks,it just will ping when I shift hard with my foot in it. Sounds like a very *tinny* tapping sound from the valvetrain. BUT,it does this on premium too,regardless of the brand of gas.

Is it the ethanol causing the pinging? Mr car NEVER pinged before that [censored] ethanol gas came on the market.

i thought E10 has been around for a really long time?
i don't even remember the last time i got gasoline that had no ethanol in it?

have you checked to see if it's perhaps lifter tick or vtc tick? both common noises in our cars.

let's hope it's not rod knock.

 

[aquariuscsm]

Nah,it`s just that light metallic pinging sound when I push it really hard between shifts. My Z only has 78,000 miles on it and I usually drive it like a lil old man. I only get the pinging on a fully warmed engine on 100F+ degree days. I`m just thinking it`s today`s [censored] ethanol blend gas. My Z31 did it,and my Olds w/3800 did it if I used really cheapy gas in it. Yeah,I`m thinking ethanol hasn`t really been common for a long time,but then again,I`m 43 years old haha.

But no,never have had lifter tick. She purrs like a happy kitten :^)

 

[Scott_Tucker]

Originally Posted By: Trinh
Originally Posted By: Scott_Tucker
It is just a marketing scam. All cars could be tuned to run on the same octane fuel.

it's not a marketing scam, higher octane is better at suppressing knock, why do you think the big horsepower guys run race fuel, C16 or Q16, etc.? the newest fad, for lack of a better word, is E85. again, this is for forced inductions, if you have a naturally-aspirated platform, you don't really see the benefits.

I'm not saying that high octane fuel is a scam, I'm saying we don't need three grades. A car that will run on 87 will run just as well on 91. The cost of producing 91 isn't much different than producing 87 as it would seem by the price, so the extra cost of having additional machinery and having to ship it separately seems like it would even out. Of course, people want to feel like they have a choice so I can understand why they do it like that.

 

[Garak]

I've only had a problem with premium (used in vehicles speced for it) a couple times. One was simply a bad batch in the old Audi, and it ran terribly for the whole tank. Such is life.

The other time was years ago, and that's getting premium at a place that hardly moved any. It was probably stale, or at least degraded. Perhaps that's what you encountered.

 

[Trinh]

Originally Posted By: Scott_Tucker

A car that will run on 87 will run just as well on 91.

but the reverse is not true, a car that runs on 93-octane won't run just as well on non-premium fuel.

it's not about choice, for forced-induction or high-compression engines/cars, you NEED premium fuel.

Originally Posted By: Scott_Tucker
All cars could be tuned to run on the same octane fuel.

no, they can't, again no offense intended but a civic isn't a performance car, you can't use your car as some sort of benchmark.

for boosted and higher-compression cars, you need premium fuel.

higher-octane fuel is better at suppressing knock, you can't get around that.

 

[aquariuscsm]

BUT,does ethanol cause pinging? The noise I`m talking about isn`t knock. It`s a VERY faint *tinny* sounding pinging that lasts only for a millisecond if I lay my foot into it between shifts.