Only the supercharged applications required 91 or higher octane per the owners manual.

Naturally aspirated applications (specifically the 2005 impala) only required 87 octane. Depending on where you fuel, this requirement can be met with regular fuel (86-87 octane locally) or mid-grade fuel (87-89 octane locally).

Premium is generally considered a waste on stock naturally aspirated applications, and if you find yourself requiring premium, then there is an issue that likely needs to be addressed.

Also, the edit feature was removed because it has been abused in the past here, at a great compromise to forum content, hence, the removal. Also please take note that it is against forum policy (and confusing as heck sometimes) to scare up threads that are greater than 6 months old.

Anomaly, rjolly87 is correct on two fronts. You are commenting on posts that are two years old. Your input is always welcome, but please respond to recent posts or start a new thread.


The NA 3.8 does not require higher octane level fuels. Anything above 87 is a waste of money.

Duly noted. However, not to be argumentative or flip, but how welcome is my input if I have to check the date of every thread I view? Kinda cuts the usefulness of the forum in half, if you ask me... What if a new user has a question that wasn't covered in that thread? Sure, I can start a new thread, but wouldn't that be more confusing by having to backlink another thread?

Feel free to view all the old posts you want ... that is why we leave them there. If you are responding to another member'* post you should check to see how old the thread is for a numbers of reasons. First, chances are the member who posted is no longer active on the site. Second, if you post information valuable to other members we don't want your nuggets of wisdom to get lost in the depths of old posts. There are other reasons, but that should be sufficient.


I also commented on your post because you provided advice I do not agree with. There is no benefit to running over 87 octane for a NA 3.8, and I would never put two cans of Seafoam in the gas tank. Half a can in the tank, half a can in the crankcase, and change the oil after 50 miles.

I Personally don't see anything wrong with Replying Old Threads No matter how old. I sort of view Your point 2kg4u, But I think its more beneficial to people (Like Me) when You search an Old thread but all Your questions didn't get answered in there. I don't about You or other people, I Say if You have something to say in any old thread go head and say it, It shouldn't be this difficult.

I suggest you both familiarize yourselves with the Forum rules which can be found here: https://www.gmforum.com/introduction...2015-a-304557/


Pay particular attention to the following section:


Bumping Old Threads

If a thread/post is more than say 6 months old, we would prefer that you not reply to that thread, but instead make an new thread with a link pointing to the old one. Most of the time, the OP'* haven't been on in years and more than likely they won't respond.
This is also called Necro bumping.

I don't know I have an 8th gen impala Base it gets decent mpg but the 7th gen is less aerodynamic I think

I like the lt1 to ls3 swaps on the 7th gen cars that is awesome and would increase fuel economy slightly