87 vs 93 Octane. Any differrence?

[Lane Slabs]

The manual says to run 87 and so did the dealer. Will the car run any better with higher octane, not as well, or the same but leaving a bigger hole in the wallet? Of course I know about the 93 octane tunes and all of that, but I am talking about an unmodified GT. Any thoughts?

[TheFANforRPM]

Always run the highest octane possible unless the manual says not to. The higher the octane the cleaner the fuel burns through the whole system. Parallel it to the chemistry test from high school. The more orange the flame, the dirtier it is, the bluer the flame the more pure it is.

The top tier gasolines are: BP/Amoco, Texaco, Shell, Sunoco, and Chevron.

Stay away from ExxonMobil gasolines. They are detergent gasolines that actually leave a "ring" throughout the lines like a ring around a bath tub after the water drains, thus clogging them up, and any other areas with deposits.

A good raw gasoline to clean your system without a gas additive is Citgo. Alternate Citgo for every 2 refills of the gasolines above and watch your mileage increase after 2 cycles. I've been doing it for over 10 years.

[chad1140]

It could be all in my head but my 2009 GXP loves street legal octane booster and Hi test. I mean look at it this way.....garbage in = garbage out. If I had you run on ramen noodle all the time, your body would run like crap.

[ghostman]

Using 93 octane on a car designed for only 87 certainly wont hurt anything. Since I work at the #5 biggest refinery in the USA, I can tell you that in the QC lab test engines for Octane certification, the premium test engines (SUL) are clean and shiny, while the regular unleaded (RUL) engines tend to get black/brown and skummy (this is raw gas without additive packages). There is no differnce in "commodity grade" gasolines shipped around the USA, as they all meet US Govt. testing standards. The only thing you are getting with "branded stations" is a guaranteed additive package at the pumps -- and that blend of additives is proprietary for each company. All gasonlines are additive packed except for that stuff sold at the off-test stations --where you don't know what your getting (Wizard, RaceTrac etc.). OK to use these on rare occasions but don't make a habit of it. Gas at major Groceries stores is also fine: its major brand stuff sold at a discount due to their purchasing power (Sams Club, WalMart, Costco, Kroger, HEB, etc.).

Some cars even pick up extra HP when you fill with 93 octane (like my wife's Odyssey van). It's nice to have that extra 10 Hp and torque when hauling lots of people/luggage on a holiday packed freeway moving at 80+ mph. Increases mileage too usually.

But it's not really economical to always use 93 Octane at a 20 - 26 cent premium per gallon. Your giving more $$ to the station owner for purely elective reasons.

BUt it's America and you have the freedom to choose 93 Octane and drive a big V8 engine if you like! That's a good thing.

Happy Motoring, we're drivers too.. and predominantly Republicans...

Ghostman.

[Jackalope]

Mine seems to not only run better on the good stuff but the mileage is better too.

[ghostman]

Originally Posted by Jackalope

Mine seems to not only run better on the good stuff but the mileage is better too.

The mileage improvement is associated with the boost in horsepower realized by having more octane to delay combustion to the optimum time.

[finallink]

Every vehicle I have owned the following simple test tells the truth.
Run the vehicle down to empty, fill it up with 87, note your mileage and how many gallons on piece of paper.
Next fill up do it again, fill with 87 and note mileage and how many gallons.
Do the math to determine how many miles Per Tank you got.
On third and four fill ups, put 91, note mileage and how many gallons it took to fill it up.
Do the math again and you have your answer.

The results are always the same, premium gas gives you more miles per tank than 87.
NOTE: I didn't say more miles per gallon, I said miles per tank.

[Kipper]

What about Sinclair gas stations? Are they quality? -Kip

[jayco59]

My two cent on octane is use what the manual says.
Bottom line is you want the gas to burn not explode. Octane is put in gas to lessen the tendency of gas to explode, in high compression engines you need the higher octane to keep the gas-air mixture from exploding. When you hear engine ping that's the gas exploding not burning. Exploding is bad for the valves.
With that said the manual on my V-6 says to run 87 but you may experience some performance boost with 89 octane (I'm assuming that's because on the variable valve design of the engine). On the 6.0L V-8 it says to use 87 (nothing about 89 for performance), the larger V-8 needs premium.
IMHO additional octane (anything over getting the engine not to ping) is waisting $. But I know from talking with other car enthusiasts, I'm talking heresy! ;-)
Jay

[Lane Slabs]

Well, I started to run 93 a couple months ago, partly because of what some of you said. The car does seem to run a little better, get slightly better mileage. However, there are some other possible reasons for this:

1. The car still has only 3,500 miles so still may be breaking in.
2. It's all in my head
3. The mileage increase is shown on the OBC, but I have been overall driving a little more "civilized."