Unleaded in a car that`s specd for premium.

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How do we really know what these gas stations are dumping in the tanks. My father told me of a gas station he knew of in the 60's that would dump some diesel in with the gas. mind you back then i,m sure the cars would not notice as long as they wouldn't over do it with the diesel fuel. I guess my point is how do you really know if there not putting regular gas in all the tanks. Does anyone ever check up on gas stations to regulate the quality of the fuel.????????
 
Originally Posted By: hemitom
How do we really know what these gas stations are dumping in the tanks. My father told me of a gas station he knew of in the 60's that would dump some diesel in with the gas. mind you back then i,m sure the cars would not notice as long as they wouldn't over do it with the diesel fuel. I guess my point is how do you really know if there not putting regular gas in all the tanks. Does anyone ever check up on gas stations to regulate the quality of the fuel.????????


It isn't even just the station that does that sort of thing, at least that's how it is here. Weights and measures comes around (I think it's once a year?) to measure the volume from the dispensers in every grade of gasoline and diesel fuel. It all goes back into the regular tank.

The gasoline has to go somewhere and it's legal to put higher octane stuff in the lower octane tank. The diesel they could spill out on the ground if they could be sure it didn't get contaminated with gasoline, but it's easier to just dump that in with the regular which is still legal.
 
Originally Posted By: aquariuscsm
BUT,does ethanol cause pinging?


In my experience at least, no. I've tried ethanol premium (which is rare here, but used to me more common) and pure premium, without any noticeable operating difference.

The only pinging I've noticed since the 1970s was on one of the last Caprices where drivers were putting in real bad gas (pure gas at that station at that time). It took a couple tanks of premium to sort everything out. The sound and circumstances surrounding it were similar to what you described.

When the Audi had the bad load of premium, it just ran bad, probably retarding the timing on its own. The other bad premium experienced (a low traffic station, as per my previous post) just kept setting of a CEL until better gas was put in; it was probably retarding the timing, too.
 
Being unleaded or not, and being regular or premium, are two totally separate things. So the OPs queston is invalid.

If a car does indeed spec premium, it needs it for best economy and performance. No mfr would EVER spec premium if if did not need it.

That said, always use as low octane as is needed. Butt dynos and hearing for knock are not always good indicators for octane requirements.
 
Originally Posted By: mechtech2
Being unleaded or not, and being regular or premium, are two totally separate things. So the OPs queston is invalid.

If a car does indeed spec premium, it needs it for best economy and performance. No mfr would EVER spec premium if if did not need it.

That said, always use as low octane as is needed. Butt dynos and hearing for knock are not always good indicators for octane requirements.

This!!
 
Originally Posted By: mechtech2
Butt dynos and hearing for knock are not always good indicators for octane requirements.


Absolutely. Obviously, when the taxi pinged from bad fuel, that certainly didn't mean that a 1990s era Caprice with a stock 305 needed premium. Sometimes an anomaly is just that.
 
Originally Posted By: 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.


The wife's former car was a 6G72 SOHC 2001 Eclipse GT. It would run fine on 87 octane in spite of the warning that it required premium.

The wife's current car is a Turbocharged PT Cruiser GT. Don't even think of using less than 93 octane. It knocks and pings badly under boost with 89. Around town with little throttle you do not notice, but when you get the turbo spooled up you definitely notice it.
 
My Grand Prix has a supercharger and the manual "recommends" premium which I have run since day one. No problem with paying a little extra, but sometimes the difference is 40 or 50 cents a gallon. That's a problem.
 
When I see knock in my logs there is ZERO audible indication of it. If you're hearing pinging while getting on it after putting the wrong grade, then you should really stop getting on it. I don't know what those blocks are made of, but I hope for your sake there are no weak links that you're severely testing...

As far as pump gas premium being questionable, I'm telling you, again, that it's all in the logs. When I get some iffy fuel it shows in my logs. As soon as a I get some fresh gas, all is well. Normally, if I see any more than a very minimal amount of knock in my logs I'll flash a 91 octane map, which also drops the knock down to zero.

I'd run the 91 octane map with 93 octane fuel all the time for added conservitism, but the 93 octane map is already conservitism, and the difference in power is very noticeable.
 
My Z`s engine has an iron block. I DID notice that with Kroger gas,it pinged the worst. HEB and Shell gas always runs great! Walmart gas always burns up really fast and doesn`t last. Weird,huh!
 
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My '62 Buick was intended for 93 and higher octane fuel, but it will run fine on 89 and higher. With 87, it will not shut off properly and will be finicky at startups.
In my case, Buick did sell a lower compression version of the same engine for use with "economy fuels", but that's not what I have.
wink.gif
 
OMG, I remember 'dieseling' in my carbureted cars! Only one left here now, so the problem is gone.

I was actually disturbed by the way my first fuel injected car turned off. So sudden and final. Fuel cut off is a wonderful thing.

But back on topic, most folks do not even understand octane. Slower burning/harder to ignite fuel is not always the best fuel. I used to retune vehicles a lot in the 80's to run well on regular, and many times a bit of fuel enrichment was all they needed. Most times we ADDED timing.

Talking about tuning across differing platforms can confuse folks, as even the same cars can require slightly different tweaks to run sharp.
 
Question to OP:- When you compared regular against premiums, was it at the same gas station? OR did you use different brand of fuel?

Talking about premium, the new Acura TL just purchased has "premium required" in the owner's manual. It specifically states that anything else will cause engine damage. Being a Honda, I would have expected "premium recommended" but that is not the case.

In the past, I have routinely used regular on the cars which had "premium recommended". I did not notice any significant drop in the performance to warrant premium. SHO, Turbo Eclipse and Maxima all had been fed regular and had enough street performance and never heard any engine pinging.
 
I normally run premium in my car because it's "recommended" (more like required). A couple weeks ago, I put in 87 because I was almost out of gas and the station I ended up at had the price jacked up 20¢. It ran that tank fine. Then I put in regular again because the first tank seemed fine. This tank doesn't seem to be going so well. The engine feels like it's been neutered. I can't wait to finish this tank.

And in the past, I would usually get a .5-1 mpg difference between 87 and 93 so it doesn't really cost all that much more. So back to 93 I go.
 
Originally Posted By: SteveSRT8


But back on topic, most folks do not even understand octane. Slower burning/harder to ignite fuel is not always the best fuel. I used to retune vehicles a lot in the 80's to run well on regular, and many times a bit of fuel enrichment was all they needed. Most times we ADDED timing.

Talking about tuning across differing platforms can confuse folks, as even the same cars can require slightly different tweaks to run sharp.


Absolutely, but we're not talking about tuning here. We're talking about stock blocks that either recommend or require higher octane fuel.

While tuning, both fueling and timing (and valve control and wastegate duty cycle, and etc) need to be adjusted. The first thing most do in turbo Subie tunes is mess with the fueling - stock likes to keep AFR near or just less than stoich even after the onset of boost. Aftermarket or pro-tunes dump it down to ~11-12 quickly and keep it there. Tip-in enrichment is important, too, to combat exactly what the OP seems to be experiencing. Add a little more fuel and maybe take away some timing and no more pinging.

Outside of tuning for fuel, a fuel suited to your stock requirements, even if only recommended, is what should (not shall) be done (I.e., running 93 octane in an engine that recommends 91 octane is a waste of money if 91 is recommended; however, 93 is just fine if 91 is required, and the stock tune is known to be aggressive - my STI, for example.)

In the end, use what's required or recommended. You're doing yourself ZERO favors by using a lower-than-recommended octane. Unless you've got an old iron block, like the OP, or a motor known for taking abuse and low octane without spinning a bearing or damaging pistons, then run the required octane. Even if you drive gently and mostly highway, where the higher octane may provide no benefit, the first time you get on it, which we all do, damage may occur. It's as simple as that.
 
I`m curious,what damage can possibly occur using a lower than recommended/required gas? What components could suffer,and how?
 
Pistons, rods, anything that rods punch holes through, wristpins and rod bearings, and exhaust valves all come to mind as potentially being harmed. Nothing major, really.
 
What exactly does higher/lower octane *do* per se? What does a higher octane gas do that a lower one doesn`t and vise versa?
 
http://forum.ih8mud.com/80-series-tech/160442-high-octane-fuel-vs-low-octane-fuel-facts-myths.html

http://www.state.mn.us/mn/externalDocs/Commerce/Gasoline_Octane_Facts_102902052227_OctaneFacts.pdf

http://www.ftc.gov/bcp/conline/pubs/autos/octane.shtm

http://science.howstuffworks.com/gasoline3.htm



Octane Facts
• Knock occurs when cylinder pressures are high. It is normal for an engine to ping a little at full throttle
because cylinder pressures are very high at full throttle. Engine knock, however, should not be ignored
since it can result in serious damage to the engine.

• High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when
cylinder pressures are high.

• If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in
switching to higher octane gasoline.

• If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could
be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a
high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.

• Almost all of today’s new cars have fuel-injected engines that need to use gasoline with a detergent additive.
They do not necessarily need high octane gasoline with a detergent additive. Generally, new automobiles
need high octane gasoline only if the manufacturer recommends it.

• Always follow the auto manufacturer’s octane recommendations in your owner’s manual.
 
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*It is normal for an engine to ping a little at full throttle*

^^This. That`s what happens to me,whether it`s premium unleaded or regular unleaded. Just light pinging,no knocking whatsoever.
 
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