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IowaCowboy
Iowa native
Premium
join:2010-10-16
Springfield, MA
kudos:1
Reviews:
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[Tech] Which grade of fuel should I use

I have a 2001 Dodge Stratus with about 80,000 miles on it. When I use cheap 87 octane fuel, it runs rough and has bad engine knock. If I pay 20 cents more per gallon (at BJ's warehouse club), I can get 93 octane and it runs smoother. In my previous cars '91 GMC Sonoma and '95 Mercury Tracer, I would use 87 octane fuel from a Sunoco Station and they would run fine. I am wondering if the Stratus calls for premium fuel per OEM specifications. Some petrol stations have 93 octane while others only go up to 91 octane. Some stations charge as little as $3.39 for 93 octane while others are nearly $4 per gallon on premium.
--
All of my CPE (including my EMTA) is customer owned. The only Comcast owned equipment in my house is the CableCards in the two TiVO boxes I own.

matt5

join:2001-10-06
Lagrangeville, NY

1 recommendation

It should be in your manual, however, I would say regular is the correct fuel. If you are having issues with pinging, you likely have other issues, and should get them looked at asap as pinging will destroy the motor in a short time.

PrntRhd
Premium
join:2004-11-03
Fairfield, CA
reply to IowaCowboy
If the gas cap area does not have a sticker stating the fuel grade, it should run on regular fuel.

Kearnstd
Space Elf
Premium
join:2002-01-22
Mullica Hill, NJ
kudos:1
reply to IowaCowboy
most 2000+ cars even if they state premium will adapt to lower octanes. A good example is my parents run their Outback XT on 89 instead of the manual's 93(premium) and the mechanic at the dealer said no harm would be done.
--
[65 Arcanist]Filan(High Elf) Zone: Broadband Reports


The Pig
I know you want to be me
Premium
join:2009-09-11
reply to IowaCowboy
Regular and put in a can of Seafoam!


MooJohn

join:2005-12-18
Milledgeville, GA
kudos:1
Reviews:
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1 recommendation

reply to Kearnstd
said by Kearnstd:

most 2000+ cars even if they state premium will adapt to lower octanes. A good example is my parents run their Outback XT on 89 instead of the manual's 93(premium) and the mechanic at the dealer said no harm would be done.

Nooooo! Your dealer mechanic is an idiot. Turbo Subarus have a pretty bad tune from the factory and can knock even on 93 octane. Running 87 octane on it will definitely shorten the life of the ring lands. It's also silly to buy a top model turbo vehicle and then be too cheap to spend the extra $2 per fillup. When something fails (and that's when, not if) the complaints will be all about how Subaru made a crap engine and not that it was fueled with water its entire life. I hope that mechanic can fix 'em because he clearly doesn't know how they're operated.

Saying cars will adapt to low octane is true but it is misleading. It's like saying your body will adapt to work on half its required caloric intake. Sure it will -- for a while. The factory spent all that time developing a timing map so the engine will deliver its rated performance over a wide range of operating conditions. Then there's a fallback map that makes sure you aren't stranded due to a bad tank of gas. Now you're asking the car to run on that map 24x7. They do have limits of how much timing can be pulled and you can still knock under throttle. That Subaru is probably pulling all the boost it can too. Anyone with free software & a laptop can see this in 30 seconds and I'd bet the farm that their ECU is not a happy camper.

Most garden variety v6s work fine with 87 because there's nothing special about them. Run regular in a Camry with no problem! The Hemi in my truck suggests at least midgrade but it gets 93 all the time because I'm not that cheap to fuel a higher-compression v8 with the minimum.

The OP's Stratus shouldn't require higher octane either. If it runs better with it, I'd look at Seafoam too, to get rid of deposits on the pistons that may be causing preignition.
--
John M - Cranky network guy


Juggernaut
Irreverent or irrelevant?
Premium
join:2006-09-05
Kelowna, BC
kudos:2
reply to matt5
said by matt5:

If you are having issues with pinging, you likely have other issues, and should get them looked at asap as pinging will destroy the motor in a short time.

I would agree. This car shouldn't knock on regular. It sounds like the ECM is putting out bad timing curves. It was suggested it may have a lot of deposits, but it would have to have a lot of blow-by from the rings or valves generally speaking.

One thing the op can do is pull a middle plug, and check for pre-ignition damage to it. It'll look melted/ corroded.

Is the engine running hotter than normal? That's also a sign...


DarkLogix
Texan and Proud
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join:2008-10-23
Baytown, TX
kudos:3
reply to IowaCowboy
I'd run it on 93 while I do a seafoam treamtment on it a few times and then go back to 87

I've heard of this kind of thing happening on higher mileage cars before

ether of the following happened
1. an octane higher than intended is used which thus causes carbon buildup (higher octane fuel by definition has more carbon in it and if the combustion isn't hot enough to burn it then you get deposits), once the deposits are there the compression ratio is altered because the volume when at TDC is less than what it was intended for the tune

2. the timing has somehow shifted and something needs to be corrected

and on the topic of newer cars adapting to lower than intended well in adition to whats been said they have knock sensored but theres only so much timing that can be pulled

HarryH3
Premium
join:2005-02-21
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Reviews:
·Suddenlink
reply to IowaCowboy
Some Mopars of that era called for 89 octane. See if you can find an owners manual to check for sure. My dad had a V6 Chrysler New Yorker in that general time frame (and I can't recall the model year) that said in the owners manual to use 89 octane. I was pretty amazed as most generic people haulers just need 87 octane.

HarryH3
Premium
join:2005-02-21
kudos:3
Reviews:
·Suddenlink
reply to Kearnstd
As MooJon stated, running lower-grade gas in a turbo (or supercharged) vehicle is NOT a good idea. The boost creates cylinder pressures FAR above those found in a normally aspirated engine. The high pressure causes lower octane fuels to spontaneously combust before the plug fires. It pounds the crap out of pistons.

fixrman
Premium
join:2003-02-10
Hatboro, PA
Reviews:
·Verizon FiOS
reply to MooJohn
He didn't say that it was running on 87, he said they run the Subaru on '89. I'd be willing to bet dollars to doughnuts as well that the turbocharger gets a very light workout, so there is no harm in using 89 octane.
--
"from a broken heart to a hole in the sky"

fixrman
Premium
join:2003-02-10
Hatboro, PA
Reviews:
·Verizon FiOS
reply to IowaCowboy
If that Stratus is equipped with the 2.7L engine, there may be many problems with it - the least of which would be the type of fuel that is burned. Those engines were notorious for catastrophic failures at nearly any time due to poorly designed PCV systems and the tendency to develop sludge no matter how well-maintained. Do a search for 2.7L failure and see how many results there are.
--
"from a broken heart to a hole in the sky"


IowaCowboy
Iowa native
Premium
join:2010-10-16
Springfield, MA
kudos:1
Mine is a 4 cylinder 2.4


aannoonn

@optonline.net
reply to IowaCowboy
said by IowaCowboy:

When I use cheap 87 octane fuel,

The important word here is "cheap", as in "low quality". Use a brand-name 87 octane fuel. If you still have problems, have your car repaired.


Lone Wolf
Retired
Premium
join:2001-12-30
USA
kudos:1
reply to IowaCowboy
I always use what the owner's manual suggests. Can't go wrong if you follow the manual.

RTFM!
--
Charlie Rangel/ Gov. Rod Blagojevich 2012 Dem Ticket Honesty is the Dem policy!


michieru
Premium
join:2009-07-25
Miami, FL
Reviews:
·Comcast Business..
reply to IowaCowboy
»www.edmunds.com/dodge/stratus/20···ecs.html

Says regular meaning 87. If you are experiencing knocking then there are other issues involved. The higher grade fuel is compensating for a already existing problem which prevents the knocking sound. I would have it checked before assuming that a higher grade fuel is recommended for your vehicle when the manual would state it was "designed" for regular.

Some vehicles do perform better at a higher grade fuel but that information is also stated in the manual as well such as 93 ideal but 89 works and 87 is unacceptable.

Do not put a fuel that's not recommended by the vehicle manufacturer unless you want premature failure of certain engine components.


Irun Man
Spartan up
Premium
join:2002-10-18
Walden, NY
reply to IowaCowboy
I had a similar issue with a 1994 Dodge Intrepid ES 3.5 V6... would notice knocking on mid grade 89 (the recommended fuel) and no knocking on premium. Dealer said there was a TSB that mentioned carbon buildup in the head that was causing preignition. If fuel system conditioners don't help, physical removal of the carbon is the only cure (and you know what that means). Try Seafoam first (through the intake mainfold instead of mixing in fuel tank).

I wouldn't bother with a teardown at this stage UNLESS you develop a future head gasket or other block problem. Less hassle and up front expense to buy premium gas instead.
--
I turned on my computer for this?

mythology
Premium
join:2002-10-16
Seneca, SC
reply to IowaCowboy
Put some jet fuel in that bad boy.


Juggernaut
Irreverent or irrelevant?
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join:2006-09-05
Kelowna, BC
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I think you mean Av gas, not jet fuel...

Kearnstd
Space Elf
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join:2002-01-22
Mullica Hill, NJ
kudos:1
reply to IowaCowboy
Av gas would likely burn up most car engines or so I have heard as it can get things a bit hotter.

I have heard people have successfully run jet fuel in a diesel though and diesel in a jet engine.(though jet turbines will literally run on just about anything that burns so that does not say much)
--
[65 Arcanist]Filan(High Elf) Zone: Broadband Reports


TypeNameHere

@spcsdns.net
reply to IowaCowboy
The problem isn't the fuel.

Check EGR valve function....because it isn't (functioning) .
THAT is where the ping is coming from.

Seafoam.....bwahahahahahahaha!!!!!!1

fixrman
Premium
join:2003-02-10
Hatboro, PA
Reviews:
·Verizon FiOS

1 recommendation

Not necessarily. The vehicle could have a cooling system issue as well causing excess heat.

Just pour Seafoam all over the car for best results... and get away. (No, don't really do that).
--
"from a broken heart to a hole in the sky"


EGeezer
zichrona livracha
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join:2002-08-04
Midwest
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Reviews:
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2 edits
reply to IowaCowboy
From repairpal, a pretty good layman's explanation;

Common Reasons for Engine Pinging

Improper Combustion Process
An engine can ping (or knock) due to an improper combustion process. A "spark knock" is the result of combustion occurring too early. Early combustion can occur from carbon buildup inside the combustion chamber, a lean air/fuel mixture, and advanced ignition timing (spark plug firing too soon). In a properly-firing cylinder, the spark plug ignites the air/fuel mixture and a flame front starts on one side of the piston and burns across the top to the other side, which creates a rapid and evenly-expanding gas that pushes down on the top of the piston. When the air/fuel mixture is ignited prior to the spark plug firing, the two flame fronts collide, causing the pinging/knocking noise.

Engine Is Too Hot
An engine can ping because it is too hot. This is another uneven combustion scenario that is caused by the air-to-fuel mixture "lighting off" by itself. If the cooling system does not keep the engine's combustion chamber temperature in check, the air-to-fuel mixture will begin to spontaneously explode. This is also called "pre-ignition."

Improper Gasoline Octane
In addition to cooling system problems, pinging can be caused by improper gasoline octane, an overly lean air-to-fuel mixture, or a lack of proper exhaust gas recirculation. The exhaust gas recirculation system (EGR) was created to neutralize engine pinging by adding a small amount of exhaust gas to the air-to-fuel mixture going in to the combustion process, which limits the peak combustion chamber temperature.

In addition to other causes provided, carbon buildup could be from worn rings.
Lean mixture could be a clogged fuel pump or injector(s)
A clogged radiator or bad thermostat could cause overheating.
Bad plugs or wires could cause misfiring and carbon buildup.
Bad valve seals could allow oil to leak into the combustion chamber, causing carbon buildup.

I'm sure others can provide more...

For some of these causes, I'd expect one or more other symptoms, like DTCs registering, a check engine light, gauge readings to be off, possibly smelly acrid exhaust, knocking and run-on at shutoff and other symptoms.

Edit - I wouldn't use AVGas, as some of that containd lead - not friendly to autimotive engines and emissions components.

And, don't depend on the gas cap to tell you. A replacement cap from Autozone, NAPA, etc doesn't have labels.