Not very nice to be so abrupt with someone honestly trying to help.

I will support minic6's contention that the 3.1 V6 with automatic/overdrive can produce great mileage at 70-75 MPH. With whatever gasoline is available at any time and any place.

I owned a completely stock 1994 Pontiac Gran Prix that got 32-33 MPG with cruise set at 75 MPH. We drove in many states Illinois to California and mileage was very consistent. We owned the car 1996-2000, probably should still own it.

I could not and did not drive those speeds in the mountains of Colorado but the car did get 31-32 MPG in mountainous terrain with no cruise.

What do you suppose GM did to the cars in that short interim to make worse fuel mileage capability?

CO,

I appreciate all the suggestions!
And I'm dumbfounded that my text could have been interpreted in any negative way. I did not wish for that. Tho, I do think gasoline formulation makes more difference than you two think.

So I'll let you two know the results of the backpressure test and the tuneup.

Maybe GM didn't do anything to make worse fuel mileage capability? Not sure why you may be thinking they did?

Lets sort this out. I did not take offence at anything written. In the years I've worked in the industry I have seen vast differences from car to car. Some get fantastic mileage, on others it doesn't. Apples and apples and they aren't the same or sometimes even close. I have no explantion for this, but there it is. Maybe it is the quality of fuel in our case I don't know. I happen to run either a name brand or a cheapy doesn't seem to make a difference in my Geo. Premium for some cars help FE mine, it's a waste of money.
I hope you find something tangable to grab on to our old Lumina is now owned by our daughter and comes no were close to the mileage it use to get with us? Wonder why? LOL On a trip to Colorado Springs there was a huge difference on milege as to who was driving!

Hey I for some reason thought you lived in Ingham county where they do have purer fuel, but you don't. It's not fuel afterall, you have same as me.
So for sure, I'm going to check into an early plug and wire replacement and see what that does. Also check into exhaust backpressure like you said. I'll let you know, thanks again!

Yep the awesome final drive and gobs of low end torque with that 3.8 is for sure going to get you that higher mileage! No fair! Wish I had that great final drive gear! I'm running 2850rpm at 75mph!
You have a great cruiser bowtieguy. Hope to join you in acetone testing next month!

How much should i put in on my tank? i think its a 19 gallon.

hockey4mnhs,

Maybe try 5oz's since this is your first tank with it. See if your engine likes the higher doses first? Next tank try 3.5oz, then down a quarter ounce every fill until you think you've found your sweet spot?

For my other Chevy, it liked 2.75oz iirc...
~Will

The most common ratio seems to be 3 oz per 10 gal of fuel, but it seems to vary from vehicle to vehicle. I just added 3 oz of acetone, 1 oz of toulene, 1 oz of xylene, 1 oz of GP7, and 1 oz of MPZ to my current fill up. I have a 14 gal tank, so I just kinda winged it with the amount of acetone and figured I'd start low. Do you really have a 19 gal tank in that Honda? Man, that is nice if you do. I hate small tanks...14 gal ain't enough for me. If I had my way I'd have at least a 20 gal tank, so gas stops would be much fewer and farther away.

I tried it with the Saturn doing my 22 mi test loop with a before and after test, and the scangauge showed no difference. It may have something to do with your local gas formulation vs mine.

I just actually started my testing w/ the current tank of gas that I have in the car, and the mixture I'm using comes from Louis LaPointe's suggestions.
I did try straight acetone in a 90 Caddy Fleetwood I had, and saw no gains from it. But that car fought everything I tried to do to it, so I figured I'd get a fresh start with my Cavalier and try a fresh mixture of "jungle juice," as I call the chemical concoction I'm using. :)