wjones14

Just got the August 2005 issue of Car and Driver, and there's an article by Larry Webster about differences between fuels. He consulted a guy who's supposedly the fuel guru at GM, and the article is definitely worth reading.

When you read this article, you learn that different brands of gasoline aren't the same, and you do get what you pay for. Cheap fuel can "coat your engine with thick deposits that dramatically affect performance. There are a number of possible conditions including sticky intake valves and clogged fuel injectors." The article goes on to say that sometimes the damage is relatively minor, and can be fixed with a bottle of fuel injector cleaner. But sometimes the damage requires that the injectors be scraped, or even replaced if the damage is really bad. If the deposits are on the intake valves, then a cylinder-head rebuild is necessary.

There is a standard called "Top Tier" agreed to by manufacturers including BMW, GM, Honda, and Toyota that lists gasolines that meet the standard. You can see the list here: http://www.toptiergas.com

FordFun

I don't doubt that and here's the list from that site:
QuikTrip
Chevron
Conoco
Phillips
76
Shell
Entec Stations
MFA Oil Company
-----That leaves me with only SHELL in and around where I live in Burke.
I've been using Exxon and BP/Scumoco.

What about putting in gasoline with MINIMUM Octane of 89 into a car
that the manual says I should put in 91 Octane or higher?

MilStang

As far as putting a lower octane in a vehicle than recommended, don't do it. I recently talked with a petroleum engineer, in relation to my job, and asked that question. Cars today are calibrated, by the computer, to specifically run at the recommended octane.
If you go higher you do not really gain much unless you reflash the computer to burn a higher percentage of air with the higher octane. As far as going lower you will have far more premature detonation that could have ill effects on your engine.

Go by the owner's manuel until you start customizing your engine and have to get a reflash.

And happy motoring!

azoufan

Quick Trip? Wow, I would have lost that bet. I use Mobil all the time, we don't have Shell around here. I have a QT just down the road from my office, I wonder if I should start filling up there all the time?

Sean

sonic98gt

Guess I'm just lucky. I've heard this argument time and time again, but I just don't buy it (the argument or the expensive gas). With a 50 mile round trip each day for work, I buy the cheapest gas I can find, which usually means Arco or Citgo. I've got over 150,000 miles on my '98 and am just thinking it may be time for a full run-through of things. She still pulls nice and strong, starts well, runs smooth, and gives me about 20-24 mpg.

CannonBaller

Exactly...

Your engine only needs higher octane if you flash the PCM or Supercharged your engine, but only because your are now running on advanced timing and/or higher compressoin. Meaning hotter running engine and more chance of detonation.

Higher Octane means the fuel is actually less combustable. Think of it as having less energy. But your engine gains performance ONLY because the timing is advanced or your running forced air.
With low octane fuel your timing actually retards a bit, this is conrolled by the PCM as you drive. Engine has a knock sensor that tells the PCM to retard timing when pinging (detonaton). This is turn means less power.

And those deposits on your engine is carbon, and mucks up heads, valves, etc. This is caused by excessive heat and incomplete burn. Mostly caused by denotatoin.

But if you car is made for regular octane then you will NOT benefit at all from higher octane as your PCM wll not go beyond a preset timing point.
There still maybe be some rouge detonatoin once in a while though. So your best sticking with the medium grade.

And that boys and girls is todays lesson in gasoline.

Giddyup

I agree with you totally. Cheapest gas that meets the minimum octane rating.

scottie1113

Amen to that.

KansasCityTim

I agree. Since moving to KC, I have avoided QT gas b/c I figured it was cheap. They are everywhere, including next door. This is awesome. I always used Chevron b/c of the Techron additive, but we don't have it here.

Stoenr

252,000 Miles, Always has started right away, runs great, Cheapest gas.
(Oil Changes 3000 or less). MotorVac(Great Injector Cleaning Machine) the last 80,000 every 20k. And all the other regular maintence on time.

Dont plan on changin a thing on the stang.
besides 93 octane tune

1trickpony

The question about higher octane has been mentioned before. A car built for regular will make a little more (2-3%) if the car has knock sensors and the technology to take advantage of higher grades. The same technology that pulls timing can advance it. Car and Driver did an article on this maybe 5 years ago. "Dumb" engines cannot take advantage of a higher octane rating. Premium cars need premium and suffered badly on the dyno let alone possible engine damage. Good news, the 05 Mustang GT has two knock sensors and a very smart ECU. At least two magazines articles have showed about 5 HP from running premium. That said 5HP probably isn't worth the price of premium.

Ranger

The vehicles I have had run between 150,000 to 200,000+ miles. Use the recommended octane but thats it.

ex-Galaxie500

Cheap fuel harms your engine? Well then our problems are solved! There is no such thing as cheap fuel anymore

05stangster

MannyA

Does anyone know where Costco get their gas from? Just the thought of going to 76, Shell or Chevron makes my wallet shrink. It's averaging about $2.54/gallon for the 87 here.

Stoenr

darn, thats Shell V-power price here. 87 just jumped from 2.29 to 2.39

05RedGT

The QT commercials around here advertise the fact that they are "Top Tier". They built one down the street from me last year and I get gas there all the time because it is usually about 2 - 3 cents a gallon cheaper than anywhere else.

moc1976

Call me crazy, but I always try to use Shell for all my vehicles.

MrMorden

All gas sold at retail in the US comes from a VERY few refining facilities. I can't believe the differences are that great...

But I have always had good luck with Chevron, and have used it almost exclusively since I read some really favorable articles about the Techron additives. So I guess I'm already "top tier."

StangerX

If you are at all concerned... the solution is simple. I've been doing it since the beginning of time. If you're running cheap gas (I run shell 87 in my 05 - $2.07 right now) and even if you aren't, run a bottle of fuel injector and system cleaner through at every oil change. That keeps deposits from building up and restores any lost power. I've always approved of this. My father passed it down to me.

If I can afford it, I try and run a tank of premium through every now and then, but most often times, I'd rather just pick up a bottle of addative and dump it in at each oil change.