I ran a few tankfulls of 89 octane to save a little money...The car just did not feel right. Idled rough hesitated on starts. I ended having to clean out my fuel system before it finally smoothed out. Never again. Shell V-Power 93 octane is all I'll ever put in my LT1!

 

depends on a lot of factors like altitude,ambient temperature,barometric pressure,alignment of the planets......
my 92 runs ok on 87 (no timing events recorded on a 1 week test)and gets its best mileage.but it didnt seem to fire up quite as quick as with the higher octanes.on premium my gas mileage goes down noticeably.so i run the middle grade stuff.
as far as cruddin up your filters and injectors etc running regular i gotta call .
it doesnt seem to bother every other car out there.i think its safe to say the vast majority of cars are using it.it actually has less additives than premium.some are good additives im sure,others are just to slow the burn.
quality to me is a bigger concern than octane.
your best to run the lowest octane you can before recording a timing event (computer pulling timing),and to use the best quality fuel available.(my fav is chevron with techron -mid grade)im at sea level with cool temps,its raining,and....theres a flying saucer coming to pick me up

 

where do you guys get 93? the higest around my area is 91.

 

i think thats the way it is in some area's

 

If you do the math, you should find that you will get 1 to 2 MPG better using premium. The cost for the additional mileage you will get outweighs the cost of premium, this is a bargain, plus you are getting better performance and helpful additives.

 

the owners manual says run "91 or better" I notice more power while running 91 over 89.

 

91 is the highest CA allows. Move out.

 

I notice 7-8 mpg better with 86 octane than with 91, that and the car runs a lot stronger. But I have a L-83 not a LT1

 

how so?

Not alot of people here understand what the octane rating means. The higher the rating the slower the burn, which means less energy per gallon of gas for higher octanes. I have been running 89 in my 96 for about a year now and I get constantly higher mileage than with 91.

 

wierd....I have an 84 Toyota pickup with the 22RE engine and it requires premium according to the book. If I put regular in it it dogs.....bad.

 

actually, the octane rating is a measure of how easily a fuel detonates; it directly does not have anything to do with burn rate. 87 octane fuel detonates similarly to an 87/13 mix of octane/heptane. a higher or lower rating itself does not change the burn rate. also, all gasoline, no matter the octane, have nearly identical energy density (calories/gallon).

the scatter in the fuel economies everyone is seeing is probably due to a lot of other things, such as the composition of the fuel (not the octane rating!), the condition of the engine, climate, etc. the octane rating changes engine operating conditions, which in turn COULD affect burn rate, but i haven't seen anything to prove this scientifically.

here's an interesting thread from another forum:
http://www.eng-tips.com/viewthread.cfm?qid=98312

as for the computer learning the octane, there indeed are knock control systems out there that have a slow learning algorithm that compensates for use with lower octane fuels. (it's basically a very very slow version of the "normal" knock control) the intent of this of course is purely to prevent preignition and trashing your engine, and not to affect performance. i do remember seeing in my owner's manual that i COULD use lower octane fuels but it was not recommended, so this leads me to believe our ECM's do have this "octane learning," but i have not verified this first hand.

 

FYI-I have a Neon with a 150hp engine.The owners manual says to use premium to realize the 150hp. If you use regular gas, your HP will drop to 132.

 

i think if you treat your vette well it will take care of you. if you feed it garbage like havoline and 87 crown gas fresh out of the bottom of the tank your vette will **** you

 

A BIG AMEN TO THAT BROTHER!!

 

no offense,but i would feel kinda dumb standing at the pump puttin premium in a neon

 

i know what ya mean.

but as Ruby Fan alluded to, the different octane gasolines at the same station have different formulas/additives. they may or may not help your car run better/more efficiently regardless of the octane.

another thing we noticed with our fleet vehicles at work is that the quality of the gasoline differed between regular and premium. at first we were using regular for a few months until we noticed the crap in the gas was clogging the filter real quickly. changing to a new station was not possible (i guess we had a contract with this station) so we were just ordered to always fill up with premium.

note that this does not apply to all stations, but it can happen.

 

About the increased mileage:

One thing to consider is that in some areas, the regular gas is mixed w/ ethanol (10%) and the premium is not. Gas with ethanol gets really bad mileage - 10% less or worse.

A friend of mine used to religiously fill his old, rusty '85 Olds 88 with premium. I finally got curious enough to ask why (after laughing at him for awhile) and he said that the difference in cost vs. mileage was enough that the premium was actually cheaper to run. He only did this where the stations had ethanol regular and good premium, otherwise the car got regular.

My 90 gets premium until I get time to datalog it to see if there is any difference.

Food for thought...

 

87 is not cheap gas.

It's DIFFERENT gas.

87 unleaded is better for some cars, 91 unleaded is better for some, 104 octane is better for some, and leaded gas is better for some.

Don't let the "PREMIUM" grade fool you. It's marketing for fools.

 

Nothing but 93 Octane in my Vette!

 

If you want to use it, hook up a scanner so you can see the knock counts. If you dont get any, stick with it, but you will very likely get them.[/QUOTE] Only a scanner will show if you are losing power do to retarded ignition from detonation with a lower octane fuel.