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I was always under the impression that 89 was better for my car than 87. however, the manual says 87...by using 89 octane, is that hurting my mpgs?

nope.

It's not going to hurt or help.

Might as well say the few pennies and go with 87.

Also, please reduce the size of your sig pic.

As Frank said, won't help nor hurt. Car was tuned for 87, use 87... no need for higher unless you're experiencing knock.

racer12306 wrote:Also, please reduce the size of your sig pic.

This. Thanks a lot mmmkay!

Diablo0 wrote:As Frank said, won't help nor hurt. Car was tuned for 87, use 87... no need for higher unless you're experiencing knock.

racer12306 wrote:Also, please reduce the size of your sig pic.

This. Thanks a lot mmmkay!

fixed

Muchas gracias... fixed in my post as well.

In a modern computer controled car, you might as well take the extra money the higher octane costs and throw it out the window while you drive.

The spark duration is controled by the PCM. The duration is long enough to burn 87 octane completly. 89 octane takes longer to burn than 87 does. Since the PCM is only providing enough spark for 87 octane gas, the remaining fuel is dumped out the exhaust. Before it gets out however, it has to pass through the cat. Over time, this unburnt fuel will cause damage to the cat, shorting it's life.

Long story short, use what the manual calls for.

unless u have no cat.

Hmm, my 2002 neon runs way better on 89 during winter months, and I tried switching over to 87 a week ago, that was a mistake. I am thinking I need to do a seafoam treatment or something. Never had a problem with it a few years ago when most gas didnt have 10% ethanol.

87 in the summer months is generally plenty fine for my car though. Winter blend around here is crappy gas, apparently.

^
i'm no gas expert but it might just be all in your head.

Most gas has had 10% ethanol since before neons were made. Whether or not it stated it on the pump is another matter. E10 has been around since I was in high school.

Ethanol is not the problem.

woodchuckssuck wrote:Hmm, my 2002 neon runs way better on 89 during winter months,

could you please clarify "way better" ?
do you have any data to support this?

umm... in contrary higher octane is actually harder to burn than lower octane... soooo ya.

just change your spark plugs every 20k. Will actually make it run better.

woodchuckssuck wrote:Hmm, my 2002 neon runs way better on 89 during winter months, and I tried switching over to 87 a week ago, that was a mistake. I am thinking I need to do a seafoam treatment or something. Never had a problem with it a few years ago when most gas didnt have 10% ethanol.

87 in the summer months is generally plenty fine for my car though. Winter blend around here is crappy gas, apparently.

They "winter-blend" all octanes and winter-blends contain less energy than summer blends, so all cars will generally run better on summer-blend gasoline. I love having to mess with the carb on my truck a bit when the gas changes...

esteinmaier wrote:just change your spark plugs every 20k. Will actually make it run better.

every 20k??? im doing it wrong then, i replace mine everyother oil change

Yeah, you are wasting money.

OEM interval is 30k.

Depends on the app. In the DD, I replace them when it starts missing. In the race car, I replace them every time I break something, so the interval is 35-50 miles.

esteinmaier wrote:Depends on the app. In the DD, I replace them when it starts missing. In the race car, I replace them every time I break something, so the interval is 35-50 miles.

I recomend anyone with a high mileage engine to run 89 as this helps prevent detonation from carbon deposit build up....

What do you consider high mileage?

My car with almost 90,000 miles run perfect with 87. I've never done a Seafoam or Mopar CCC treatment. I did do a minor cleaning back at about 15,000 miles to clean out any oil that had made its way in because of the PCV, but since then nothing.

hmm, this thread is very informatifve, I always was under the impression that the higher the octain, the better and smoother my engine will run. HOWEVER, ive used 91 octain, and higher before, and it shakes like a paint mixer with that stuff. With the lower 87 octain, it seems to run smoother. I was just worried that a lower octain would indicate lower quality, and may hurt my fuel filter, etc..... learn somethin new every day....

Octane has no relation to quality.

Quality is based on the brand and practices used.

also dont worry about our fuel filters, i believe their warranty is lifetime

Filters are not covered by a warranty. Ever.

Our fuel filters are integral to the regulator in the tank, so to change one you must change both, essentially. Whether or not there is a such thing as a "lifetime" fuel filter is a whole other story. Personally, I'm thinking about plumbing in my own serviceable in-line filter, for piece of mind.

And yes, as Frank said, octane has nothing to do with quality. The higher the octane, the slower the fuel burns. That's it. Having said that, higher octane gas is actually less volatile (explosive) than lower octane. The idea is to prevent detonation in high compression and performance engines. I don't know why there are so many misconceptions about fuel and ratings.

OB wrote:I don't know why there are so many misconceptions about fuel and ratings.

I'd be willing to bet that >90% of people who talk about octane, fuel and the ratings know jack shit about octane, fuel and the ratings.

OB wrote: I don't know why there are so many misconceptions about fuel and ratings.

Could be due to the marketing of fuel. Maybe more in the past than now, but none the less, the "Premium Grade" fuel allegedly contained more cleaning agents,etc. than the lower grades. Whether this was truth in advertising or not, ?

But EPA sort of changed that. All grades now must meet the same specs for quality.

There is still a lot of that "old school" stigma left over.

I consider high mileage 100K and above, most vehicles that have that high of mileage are probably all carboned up inside and the built up carbon causes hot spots and detonation which is why running 89 helps them from detonation.
Our cars with basic bolt ons can run pretty good on 87 octane, the magnum engines require 91 or higher due to the performance components of the engine. The magnum motor can run 89 or less, but performance is downgraded as detonation may happen and the pcm will pull ignition timing.

OB wrote: Our fuel filters are integral to the regulator in the tank, so to change one you must change both, essentially.

I found out you can actually change just the filter. It's a dealer-only part, but apparently just the filter can be changed. Am I going to drop my tank to do so? Hell no...

I've thought about an in-line as well.

i have heard that they are service free. thats what i heard.