Gas Mileage Sweet Spot

**9t8z28** · 03-21-2008, 04:29 PM

Originally Posted by camarojunky74

lol, no thanks, no one no how will convince me otherwise without some cold hard facts,

X2, I ain't ever gonna dump that crap in my engine!

**intheclouds1977** · 03-21-2008, 05:10 PM

Along the same note, where at slower speeds does 6th gear start becoming less fuel efficient than downshifting into 5th gear? There's a point in there somewhere that running undergeared in 6th is worse for gas mileage than running higher RPMs but properly geared in 5th...50mph?

**Finally** · 03-21-2008, 05:22 PM

Originally Posted by intheclouds1977

Along the same note, where at slower speeds does 6th gear start becoming less fuel efficient than downshifting into 5th gear? There's a point in there somewhere that running undergeared in 6th is worse for gas mileage than running higher RPMs but properly geared in 5th...50mph?

I'm gonna say that yeah it's 50mph, since the owners manual says to shift to 6th at that speed. Usually you can play it by ear and listen for that groaning bogged down sound if the engine is turning too low. That being said, I usually go no higher than 5th around town for practical reasons (hills, turns, or that moron who just has to pull out in front of you and go 20 when there's no one behind you for miles).

**rotwiler** · 03-22-2008, 08:31 PM

Originally Posted by Finally

I was just thinking in terms of dirty fuel injectors. There's a number of products out there that can be added with a tank of gas to clean injectors. Just threw seafoam as an example because I've heard of people picking up 1 or 2 mpg from that back when I worked at a repair shop a few years ago.

I agree with you though about that bullshit with people dumping crap down their brake booster vacuum hoses. Only results are probably ruined cats and a failed emissions test.

GM makes a top engine cleaner for a reason and seafoam is very simular and cheaper,
I had to use Seamfoam, my car was pinging and nothing I did but backing the timing way back would help. With the type pistons we have, they tend to build carbon on the top and it causes the ping issues. I was told while having the car dyno'd to try the gm top engine cleaner or seafoam and it worked great, now I use it every 10k to keep it clean, I use Lucas fuel system cleaner a couple times ayear also. Other than that I use Penzoil full synthetic for oil.

I haven't tested my cars gas mileage since it was stock and I was able to hit 27mpg on a reg basis. Now with the 3400 stall converter and long tube headers I decided to go through a tank and see the mpg now.. Isn't fair to compare to the 27mpg, since this time was highway 30% and 70% city and I tend to launch hard all the time, I averaged 18mpg. I figure highway only I should be able to hit at least 25mpg still.

**Silver Streak** · 03-22-2008, 08:45 PM

02 A4.. 110k miles.. 3600 stall, headers, true duals, 373 gears, after market suspension and 12 bolt... I get 18 in the city.. and between 20-22 on the highway.. but did take this pic when I went up to Cincinatti for the car show.... explan this one...

**camarojunky74** · 03-22-2008, 11:32 PM

Originally Posted by Silver Streak

02 A4.. 110k miles.. 3600 stall, headers, true duals, 373 gears, after market suspension and 12 bolt... I get 18 in the city.. and between 20-22 on the highway.. but did take this pic when I went up to Cincinatti for the car show.... explan this one...

lol, you tossed the car in nuetral

**jimmybling31** · 03-22-2008, 11:47 PM

i get 29 in my automatic when I tune i for gas mileage. it does horrible as far as how fast it is, but it gets good gas mileage. the only time I used it was when I was going to alabama and I knew I could change it back when I got there. ( I did change it to my normal tune when I got there btw)

**camarojunky74** · 03-22-2008, 11:52 PM

Originally Posted by rotwiler

GM makes a top engine cleaner for a reason and seafoam is very simular and cheaper,

gm also made 4 cylinder camaro's, and dex cool.
your point?

Originally Posted by rotwiler

I had to use Seamfoam, my car was pinging and nothing I did but backing the timing way back would help. With the type pistons we have, they tend to build carbon on the top and it causes the ping issues. I was told while having the car dyno'd to try the gm top engine cleaner or seafoam and it worked great, now I use it every 10k to keep it clean, I use Lucas fuel system cleaner a couple times ayear also. Other than that I use Penzoil full synthetic for oil.

did you ever check your knock sensor for malfunctioning before taking such drastic measures?

another thing, i am not on here talking bad or saying people are wrong, im just saying as a qualified technician i wouldn't recommend this to my enemy's, there is no facts stating this stuff does any good.

i had 155k miles on my 99 before it sadly got laid to rest, a4 btw, original engine and trans. i took this car weekly for years to the strip waiting for it to blow so i can start on my forged gmpp 427, no luck, this car soared 13.1's consistently with a lid and catback,

not once did i use anything but scheduled maintenance.

**jimmybling31** · 03-22-2008, 11:55 PM

Originally Posted by camarojunky74

gm also made 4 cylinder camaro's, and dex cool.
your point?

did you ever check your knock sensor for malfunctioning before taking such drastic measures?

another thing, i am not on here talking bad or saying people are wrong, im just saying as a qualified technician i wouldn't recommend this to my enemy's, there is no facts stating this stuff does any good.

i had 155k miles on my 99 before it sadly got laid to rest, a4 btw, original engine and trans. i took this car weekly for years to the strip waiting for it to blow so i can start on my forged gmpp 427, no luck, this car soared 13.1's consistently with a lid and catback,

not once did i use anything but scheduled maintenance.

I use seafoam every once in a while. my car needed it when I got it. it had some serious build up when I got it

**Silver Streak** · 03-23-2008, 07:14 AM

Originally Posted by camarojunky74

lol, you tossed the car in nuetral

Lol.. very good.. coming down from the mountains around Virginia.. throw it in neutral.. and you coast at 80 for miles..

**intheclouds1977** · 03-23-2008, 07:31 AM

I use seafoam in a truck I have every oil change. Years ago it had a severe misfiring problem from buildup in the intake/upper cylinders. I did 3 seafoam treatments through the brake booster vacuum line and it cleaned everything up. No more misfiring. Now I use it for regular maintenance. Haven't had a chance to run it through the LS1 yet, but it is one awesome product for sure. I also run one can through the tank every 3k miles.

**rotwiler** · 03-23-2008, 08:54 AM

If it was the knock sensors then the seafoam fixed it.
No reason for me to argue the Seafoam point, cured my issues and guess that is whats important.

**Snowboardr18** · 03-23-2008, 10:44 AM

With my procharger, I get 30 mpg highway cruising 75-80.

**camarojunky74** · 03-23-2008, 10:45 AM

Originally Posted by rotwiler

If it was the knock sensors then the seafoam fixed it.
No reason for me to argue the Seafoam point, cured my issues and guess that is whats important.

well, then your right, if it fixed the problem at hand then no complaint there, i just grow skeptical of pour this in and fix everything you know?

well keep on trucking big dog,

**Finally** · 03-23-2008, 05:40 PM

Originally Posted by rotwiler

If it was the knock sensors then the seafoam fixed it.
No reason for me to argue the Seafoam point, cured my issues and guess that is whats important.

Now that I'm hearing more and more people endorse this and doing some more researching of my own, I'm going to retract my criticism.

You really just can't help but think that pouring fluid down your intake seems 'unnatural'. But maybe not.

**Cronex** · 03-23-2008, 08:13 PM

Originally Posted by third_shift|studios

IT'S all about the tune, man.

+1 Agreed.

**richard head** · 05-04-2008, 11:43 AM

i'm doing something wrong I just know it. Maybe its the 160k w/ stock pcv buildup or something but my best is about 23.5 pure highway goin 68-70. I'm gonna go seafoam it I think.

**splitfinger09** · 05-04-2008, 05:50 PM

Originally Posted by 9t8z28

How are you all figuring out your mileage?

Fill your tank up, reset your trip odometer. Drive a couple hundred miles and then fill your tank up. Take the miles divided by how many gallons it took you to fill up and voila you got it!

**wildbanshee** · 05-04-2008, 06:21 PM

had a 95' z from 32k-178k miles....265 miles per tank(14.8 gallons) regardless of on the highway, city, burning tires or driving like a granny..let me take that back heavy highway at 80mph maybe 285miles per tank. I now have a 2000 SS 6spd...on 13.8 gallons i get 275 to 300miles. I had a 4 hour in the SS drive in a 55mph zone -at 325miles i had a 1/4 tank left...
Seafoam sometimes (makes me feel better) lucas every couple oil changes-never had a major repair in the 95'

**02SOMZ** · 05-05-2008, 06:24 AM

Based on mileage versus pumped gallons, the last three tanks have averaged 22MPG... 90% city and 10% highway driving... Looking forward to a long highway cruise to see how it goes...