Premium recommended?
 

When Gm says this, what do they really mean?

Do they mean you should only use 92+ octane?
Do they mean you should use 92+ octane when possible, but the car will "live" on 89?
or does it mean you can run it on 87 octane and occasionally put the good stuff in it or put in a octane booster?

I had a 2006 Impala SS with the 5.7L and it recommended the Premium and that is all I used. I always wondered though.

Yeah, I'm interested in the answer too. To me it sounds like they'd rather you use 92+, but you can use a lower grade with a slight loss in performance. Now it seems if they only wanted 92+ they'd say high grade only.:iono: Least that's my take on it.

This conversation has already been had elsewhere - but the compression ratio on the LS3 (V8) needs premium. Same as the LS2 (the '1 could run on crude oil though).

Its like the Vette in the stats, recommended but not required...The compression on the v6 is higher(11.3 vs 10.7), but does not require premium...You will lose some top end power as the computer dials things back, but lots of Vette guys are running regular right now with no ill effects other than the loss of some top end...Sorry tried to copy the table from the press release, the spacing did not come over well....

http://wilsonniblett.wordpress.com/2...press-release/

Thanks. That is what I was looking for. I am fine with losing a little top end, since all I see where I live is the weak V6 'Stangs. I just did not want to do any major damage.

There has been a lot of confusion, but it appears to be like the Vette in that regard...

you will lose more than just top end.

lower octane fuel will hurt your gas mileage in a car that is made to run premium and it will also pull from your power. yes you can run regular, but you are better off running at least 89 or higher or the manufacturer's recommendation.

i run 93 octane unless i cant find it then i will run 91 and ill add a bottle of STP octane boost. ive run 89 on one fillup but i only put 3 gallons in to get me to a place with higher octane gas. 87 has never touched my tank.

another thing to keep in mind is that a 3 pt octane booster will not bump 89 up to 92 octane. Under the North American octane system AKI (Anti-Knock Index) pump fuel is graded as (RON+MON)/2. Meaning if a fuel has a RON (Research Octane Number) of 96, and a MON ( Motor Octane Number) of 90 its AKI would be 93.

basically, you add the octane rating to the MON. so for our 89 octane the MON is roughly 90 and the MON is 88. add 3 to 88= 91

91+90=181
181/2=90.5 octane.

so in effect you are getting 1.5 points even tho the bottle says 3 pts.




here's a good writeup with MON and RON testing of octane boosters

http://volvospeed.com/Reviews/octane_boosters.html

ONLY 91 here in Cali, except for the Union 76 100-Octane unleadded racing fuel @ 15.00/gallon:mad0259:

and thats part of the pollution problem over there... that on top of the fact that there are billions of cars on the road over there...lol

i be running the highest avail. which is 93 here. i want all my ponys acounted for.

93 during the week, 112 on the weekends...lol

How does 91 increase pollution?
Is that 112 unleaded?

comparing it to 93 and the fact that with that being the highest available, most people will put 87 in their cars as it is the cheapest, lowering your emissions and performance. multiply that X's the number of vehicles on the road out there in Cali at any given pt in time, and you wonder why everything has a sticker that says "has been known to cause cancer in california" its not the product, its the shit-ton of smog created by the millions of cars on the roads over there.


and yeah, its unleaded... tho they have 113 leaded but i wont mess with that.

My 2 cents worth
 

With the new computer controlled engines, it would appear that octane rating is not as critical to prevent pre-ignition as in older engines. These engines will self adjust and run on 87 octane. However, as stated by others in this thread, you will lose some performance and in my experience some gas mileage (1-2mpg).
Now the economics. 92 octane is generally $.20-.25 more than 87 octane. My logic says that in a typical 20 gal. fill up, I'll pay roughly $4.00-$6.00 more per tank. In my opinion, that aint bad for a tank of higher performance, and better gas mileage. Just a thought.
:thumbsup: