john6699

I read that premium is required. What would happen if I ran it on regular and does anybody do that

horseshoez

iTrader: (2)

Some folks have been reported to run Regular or Mid-Grade. The long and short of it is, running a lower grade fuel will negatively impact performance and fuel economy.

justnspace

iTrader: (1)

the ECU should scale down timing to prevent knock. this will scale down power and fuel economy.

losiglow

iTrader: (1)

Ah, the ol premium vs. regular discussion. Well, I guess I can't complain. I recently posted a lightweight pulley thread which has been discussed ad nauseum.

There s a fair bit of argument on the subject, but bottom line is, the engine has a pretty high compression ratio, which warrants the use of premium fuel. If you consider the science behind it, premium has more octane which prevents pre-mature ignition (spark knock) of the fuel/air mixture before it's supposed to ignite. Theoretically, if regular is used, it will result in more spark knock which can result in engine damage if done long term and reduced economy and engine output in the short term. Some have reported no problems with regular, though it would be difficult to assure there's no problem unless you were meticulously monitoring fuel economy, spark knock and engine power. Like Justn said, the ECU will pull timing to help avoid knock but this will reduce engine efficiency, usually erasing any price savings from the lower cost of regular.

I'd recommend using what the manufacturer indicates. But putting regular in will not cause the engine to blow up. At least not in the short term.

thoiboi

welcome


ad nauseum is correct:

https://www.google.com/search?q=site...hrome&ie=UTF-8

horseshoez

iTrader: (2)

Just to be clear, high(er) octane fuel will not prevent premature ignition of fuel, this is called "pre-ignition", a condition which will destroy an engine in only a few rotations. What higher grade fuels are designed to do is to reduce or eliminate "detonation" (aka. "spark knock", "knocking", and/or "pinging"). Detonation is the spontaneous combustion of small pockets of "end-gas" on the far side of the combustion chamber well after (in relative terms) the spark event.

losiglow

iTrader: (1)

Pics of the long term results of spark knock. It's enough to scare me into using premium:

Spark Plug


Piston Head



Cylinder head



Valves

losiglow

iTrader: (1)

My bad. I often get the two confused. If I'm correct, the end results are similar.

horseshoez

iTrader: (2)

Please refer to my previous post; the damage in these engines was not caused by spark knock/detonation, and not directly caused by the grade of fuel. That said, prolonged use of low grade fuel where detonation is persistent can gradually cause enough damage to cause the pre-ignition which damaged these engines.

losiglow

iTrader: (1)

So what are the results of detonation then? The photos I posted are from posts/blogs that referenced detonation.

horseshoez

iTrader: (2)

Prolonged heavy detonation can damage spark plugs and valved (but not to the extent shown), and that damage can in turn lead to hot spots in the combustion chamber which can cause pre-ignition. So, indirectly, consistently using low grade fuel can ultimately lead to pre-ignition.

The flip side is light detonation is actually considered beneficial and highly efficient by many engine designers. The best place for spark timing to be is set relative to the grade of fuel currently in use, the current weather conditions, and the current engine RPM/load, is right at "incipient detonation"; the point where a fraction of a degree of additional spark advance will cause detonation to begin, but a fraction of a degree less will result on slightly less power. The beauty of modern engines is they constantly monitor detonation and keep things right at that knife edge.

losiglow

iTrader: (1)

Thank you for the insight. Learn something new every day

I'll stick with premium.

Also OP, keep in mind the additional cost of premium is usually around $.25 a gallon. Assuming 15K miles per year @ 24mpg, this would equal 625 gallons or around $150 per year. I'd be happy to save $150 a year but I think it's a bit like oil changes. I'm willing to spend the extra $$$ on synthetic and more frequent oil change intervals (literally one more per year) to prevent possible engine damage. That results in a cost of around $80 or so per year in oil (additional change and increased cost of synthetic). Of course, to eat my own words, I had my original engine crap out from bad oil rings at 130K miles so maybe it makes no difference

john6699

wow thanks for all of that

john6699

I just checked at Costco premium gas is 50 cents more a gallon. Dam Dam what now Honday Accord

a35tl

Premium is typically $.60 - $.70 more in my area but I still choose to use it.

TheMuffinMan

iTrader: (1)

If you can't afford the ~$5 price difference every week or so maybe you shouldn't have purchased a $40k car requiring Premium?

Honestly I'd be more concerned with the MPG than Premium vs Regular.

echodigital

I go with Shell in Canada. The advertise as not having any ethanol in it.

horseshoez

iTrader: (2)

Of course what was once a $40,000 car is now a $5,000 car. Just the same, if you want the size and space of a TL (or other Acura) but don't want to pay for Premium fuel, buy a Honda.

sockpuppet

Last time I checked, Costco sold Shell gas. But no Airmiles...

justnspace

iTrader: (1)

I like that comparison better, because of the low cost of entry for a used model

dregsfan

Jeez! In CA I've never seen premium more than 25 or 30 cents higher than regular, with 20 cents being most common.

CruzanTLSH-AWD

One time I put 89 in by a mistake right before winter park up........ I did not sleep for months lol!

Bat-1

Keep in mind the ratings at the pump are the minimum octane the fuel contains.

The TL calls for 91. In most sea level areas Premium is 93. Regular is 87. Mid-grade is a mix of the two, so 90 minimum. A worst-case scenario (if both the regular and premium at your gas station contain only the minimum octane) is the mid grade you buy contains roughly 1% lower octane than recommended (not required) by Acura.

If you believe a motor made to be sold to the non-racing masses is going to be engineered so tightly that this could possibly have any effect then you're exactly the type of person for whom Premium was invented.

There is no law against flushing money down toilet and if it makes you feel good then it may be worth the extra several hundred dollars a year using premium will cost.

In 30 years I've never put premium in any vehicle I've owned and never had any issues. And that includes an '88 Kawasaki ZX10, which at the time was the fastest production vehicle ever made. At 997cc that motor actually had to work to deliver that performance. Owned it for 15 years, ran it only on regular. Maybe above 130mph there may have been some performance loss but I never went there.

horseshoez

iTrader: (2)

@Bat-1, keep in mind you cannot prove a positive with a negative.

losiglow

iTrader: (1)

No point to this post, but I purchased ethanol free 88 Octane one time and never felt a difference. Maybe the lower octane cancelled out the supposed increased power with having no EtO. That's probably thinking too much.

JT4

It amazes me that this same topic comes up all the time, and it's not just on AZ. This topic constantly pops up on the Lexus forums, Audi forums, BMW etc...

In my over 30 years of driving, I know people who have never had an issue using regular all the time regardless of the octane requirement. And I also know others that have had issues from the long term effects of using a lower octane than what is required.

IMO everyone should use the gas they want to for their vehicles. If you lease your vehicle it probably won't matter since you will turn it in long before the long term affects of using the wrong octane could have an effect on your vehicle. But if you own your vehicle, and plan to keep it a long time using regular when premium is required might catch up with you one day.. Or maybe it won't..

I'm not taking that chance, for me it's simple, if my vehicle requires premium I use premium regardless if it's a lease or if I own it. IMO the cost difference between regular and premium grade is cheap insurance to keep things running correctly..

jim_c

Don't believe everything you read on the internet!

SkN012

Shell V-Power for the past 12 years. The only 91 octane premium with no ethanol in my area. Started using it on cars that don't require premium to keep the engine clean, get better mpg and the better throttle response.

horseshoez

iTrader: (2)

Ummm, no, Shell V-Power will not keep your engine any cleaner and, unless the engine is designed for Premium fuel, you will get worse fuel economy.

SkN012

Higher octane fuel won't leave less residue after combustion in the cylinders?

And yes on my 2 previous cars that didnt require premium fuel (2001 Altima and 2006 Accord) had better mpg with 91 octane. More octane better explosion so you need less fuel to acheive same performance.

horseshoez

iTrader: (2)

Primer: The higher the octane the cooler and slower the burn (fuel in engines does NOT explode, it burns as in a whoosh across the combustion chamber), and a cooler and slower burn yields less power and more deposits. In addition, due to the extra additives in premium fuel, there is slightly less heat (power) potential per unit of fuel compared to regular.

Untrue, in fact, in lower compression engines not designed to run with premium will be less clean when running a fuel with higher octane than recommended due to the cooler burn and yield a lower fuel economy. Exactly who is telling you otherwise?

the_razor

Good info, my car pings when I use Shell 91 which is no ethanol. But when I fill up with Petro Canada 94 which as per their site states 10% ethanol no pings. Based on the higher octane cooler and slower burn theory I am thinking of continuing Shell 91, but the slight ping that I hear will this be an issue down the road ?

SkN012

So for the same amount of fuel injected, you wont get a better power output with premium?

My previous odometers with a full tank of gas.

horseshoez

iTrader: (2)

Correct, unless you have a high compression engine which leverages the anti-detonation properties of premium fuel by increasing the pressure/temperature of the intake charge (a product of the higher compression ratio) prior to the spark event, your fuel economy will be slightly lower. That said, the difference is typically small enough unless you put your engine on a stand and connected to a dynamometer and use it to measure the Brake Specific Fuel Consumption (BFSC) which measures the specific fuel consumption for producing one horse power for one hour, you will not be able to detect the difference.

losiglow

iTrader: (1)

Horseshoez is pretty much on point with all of that. I've had folks tell me their cars run better on premium, even if it only calls for regular. I'd say it's largely placebo. Empirical evidence is difficult to gather between the two because even slight driving conditions can cause a difference in MPG, making it seem think they get better mileage. If the car that only calls for regular, truly gets better mileage with premium, I'm guessing that premium may be an option which isn't uncommon with some cars. It may be a possibility that a pinging engine would benefits= from higher octane fuel if it runs especially hot for whatever reason. Maybe really hot weather with constant stop and go driving or an inefficient cooling system would do it. An overly hot running "regular gas" engine could benefit from premium, though in that case you'd obviously want to figure out why it's running hot and fix that rather than running premium to keep it from pinging.

Personally, I just stick to what's recommended. I use regular in the Pilot and premium in the TL. Funny thing is, they have nearly identical engines. Both are 3.5L's except the Pilot has that awful variable cylinder management (which I hate) and has a 10.5:1 compression ration as opposed to the TL's 11.2:1 which likely explains the difference in octane recommendation.

SkN012

Thanks for the info. This community is knowledge as always. I guess the bottom line is to stick to manufacturers recommandations. Yet again, the oder day I had to gas up but only had a Petro-Canada nearby. Tried the 94 octane with 10% ethanol and felt a better response. Another placebo effet?

Bat-1

Now let's talk about motor oil

The more you pay for it the better your car runs and the longer it will last. Those marketing guys wouldn't fib you, right?

CruzanTLSH-AWD

Made the mistake of putting 87 in my Integra 1 time.. Lesson learn never again. Ain't cool having sputtering issues when it's -17F in the middle of the Alaskan Highway. As for the TL I have a tune on it so 93 is what it will be running until I make most for E85. As for oil? lol ENEOS Sustina is all I use now 5w-30.. 0w20 on my Accord.

TheMuffinMan

iTrader: (1)

Do you advertise when you've sold cars that you don't run the recommended fuel in them? I 100% would immediately walk away if a seller told me that.

Regarding oil, you can theorize however you'd like - whether your Wal-mart lube job is sufficient or if the $80+ Amsoil ones are worth it. That's easily tested with Blackstone though.

https://www.blackstone-labs.com/

Of course marketing plays into some of the popularity of oils and gas but there's also a reason some are more expensive than others.

Anicra

I see regular and I always think of when it was regular (Leaded), unleaded and Premium