After hearing great things about SF, I put a can into my tank (Tahoe) after filing up yesterday. It *seems* to be running a little better already, but that may just be me paying more attention to it than before. Anyway, I was wondering if I can improve gas mileage with it and how often to use it.

For the first several years, I was able to drive somewhere between 310 and 330 miles on a tank doing mostly city driving. Maybe a little more or a little less, but I could count on about a 315-320 or so average on a tank. Now, I'm lucky to get 280, and 270 is more the norm. The other problem, I don't know if related, is that I went out to West Texas a couple of weeks ago and got horrible gas mileage (75% of what I've gotten on the road). That day I was driving into a strong headwind and I think that accounts for some of it, but the engine performance isn't the same.

With the price of gas as it is, I'd like to get that mileage back up to where it was. I've got a new air filter in there, the fuel filter is about a year old, and I change the oil regularly. I don't, however, think I've regularly put a fuel additive in -- maybe 3-5 times total over its 5 year life. And I run the 87 gas.

All suggestions welcome.

I did this to my car last semester, and it seems to run better but I haven't really noticed an increase. If at all it would be around 1-2 more mpg.

Tahoe (huge frontal area) + headwind = lousy gas mileage.

5 year old Tahoe will not get much more mileage. I think its best is far behind you.

put in a CAI, a dual exhaust, and a snorkel, that'll give you at least another 1-2mpg and 20 hp all for the price of $1500

run some thru the brake booster line like you are supposed to to see any real benefits.

I second the brake line. Pull the vacuum line off of the brake booster and pour a half a bottle or so of Sea Foam down there. Let it sit for a few minutes, then crank it up. You will see a whole bunch of white smoke at first which is supposed to be all the impurities burning off. Your engine should run smoother, but I would not count on a huge gas mileage increase. Thanks.

Where do you live? The decreased mileage could be the result of mandatory 10% ethanol.

***EDIT: I didn't see the thread that was recently posted here specifically about gas mileage. I do apologize since most of the info is the same. I pulled my post from a totally different car forum. Not trying to steal anyones thunder!***

As some of the posters above me stated, SeaFoam is primarily meant to be run through your brake booster line. This will clean out the vast majority of the carbon buildup in your engine. Obviously, this is more beneficial to an engine that has more miles on it (and thus more buildup). However, it can also be run through your oil (as in, you can put it straight into your engine through the oil cap) or through your gas tank as you did (to clean your fuel injectors and other fuel system parts).

This is mostly meant as an engine treatment and a preventative measure to get the most life out of your engine.

If you want better gas mileage due to the rising cost of gas, there are a few suggestions I have seen online. This post was actually taken from another forum (and the poster on that forum took it from somewhere else, so it's all good ):

Gas Pumping Tips:


Gas is most dense when it's cold.
Gas expands when it heats up. Easy to understand right?
-So buy your gas very early in the morning when the ground is coldest.
-All stations have their tanks underground, so the colder the ground is
the more dense the gas is. Buying when it's hot out is bad, the gas has
expanded some and a gallon isn't a true gallon anymore.
-No gas pumps have temperature compensation on them, you just get screwed
when it's hotter out.
-The gas tanker trucks however, when they are filled, are adjusted for
temperature compensation... nice to know the consumer is the only one screwed...

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Gas pumps pump both gas and vapor, you pay for both.
-So fill your tank on the slowest setting the handle offers to keep
the vapor production while filling at a minimum.
-Every pump has a vapor return in the hose. The more vapor that
you pump in while filling there is, the more that goes back into the
hose. Meaning the more you pay for nothing! Boo!
-Each handle should have three locking settings, choose the low one,
the one that pumps the gas the slowest.
-No need to pay to pump vapor that goes right back into the hose.

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Gas evaporates very quickly!!
The tanks underground in the stations have floating roofs inside them.
This floating roof sets on the gasoline itself at all times minimizing the
contact the gas has with the above atmosphere of the tank.
Our cars do not have internal floating roofs.
The less gas we have in the tank, the more atmosphere is in there in its place.
Which means there will be more evaporation of our fuel happening.
-So try to keep your tank over half full at all times.
-The more full you can keep it the better, this will minimalize the evaporation.


One more thing...
If there is a truck filling up a tank when you pull into a station, pull back out
of that station. Most all undergound fuel tanks have a small amount of sediment
in them. When they are being filled, that sediment is being kicked up into the
body of the gasoline in the tank.
This sediment will settle fairly quickly, but if you pump from that tank with the
sediment swirling around in there... well then it'll go into your tank. Boo!
-So no pumping when there are filling trucks present.



There has been some argument regarding some of the above information, but for the most part it is all accurate and helpful. Take it for what it's worth...most of the tips do not force you to go out of your way.

As a side note, another option to save money on gas would be to just buy a more fuel efficient vehicle

[This message has been edited by BullsAndBears (edited 3/19/2008 6:05p).]

quote:

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The tanks underground in the stations have floating roofs inside them.
This floating roof sets on the gasoline itself at all times minimizing the
contact the gas has with the above atmosphere of the tank.

---

I've installed many underground fuel tanks. They are doublewalled fiberglass, nothing else. The "floating roof" is on large tanks in refineries or distribution centers, not at the neighborhood gas station.

Also, ground temperature is relatively constant. The temperature varies by season, but only a tiny fraction of a degree per day.

That point is, indeed, one that many people will argue with. I can't attest to the presence of roofs inside the tanks.

I do know that the ground temperature does, in fact, remain relatively cool, even in hot weather conditions. That was one of the points that seems to be rather moot. However, there is no harm in simply going to get gas earlier in the day...it's worth it to try, even if the positive result is negligible.

And as a side note, in Canada they actually charge 10 cents per gallon MORE from roughly Midnight to Noon (the presumably coolest hours of the day) because of the idea that the ground is cooler and thus the gas is more dense. Just something to point out.

Driving into the wind with a high profile vehicle will occasionally cause your computer to screw up the fuel/air mixture, and in some cases, a dashboard indicator light may come on.

i always feel a difference when i use it through the bbl.

NOTE- if you are going to put this in your oil, do it ~100 miles before an oil change. You don't want that loose junk flyin around your engine. Seafoam will knock some of it loose, but you need an oil change to get it outta there.

I don't get a couple of things (ignorance, no doubt): first, what does the brake line booster have to do with the intake and fuel system, and second, where does the blb send the stuff that the gas tank won't?

The brake booster line is a direct vacuum line into the engine (of course, the engine must actually be running for the line to have any vacuum suction). Basically, the way in which the SeaFoam circulates inside the engine when put through the line is what cleans out all of the internal carbon. Running it through the gas tank will only clean the fuel injectors. The most obvious proof of this is the visual result of putting it through your brake line. With your car on, pour roughly half of the can in SLOWLY through the line. Smoke will almost immediately start coming out of your exhaust. Once you have poured about half of the can in, take the vehicle for a "spirited" ride for about 10 minutes (in other words, get up into the higher RPMs). You will notice that a LOT of smoke will come out of your exhaust as you do this; this is the result of all the carbon being cleaned out.

I would suggest that you do this method in an open area where you wont bother any nosy or overly concerned neighbors. Then again, if you don't care what they think, then do it wherever you please. Just be advised that, depending on how dirty the engine is, you WILL let out a lot of white smoke. If you YouTube "Seafoam," you'll find a couple videos that show this.

The smoke that I described from this method will not occur if done through the gas tank. That's why I said the cleaning results are best seen when done through the bbl.

**Note: If you decide to pour through the bbl, make sure to do it slowly. You will notice that your engine will begin to stutter if you pour too fast and the engine will bog down. It's not bad, but I would prefer to stay on the safe side.

Any idea where the blb is on a Tahoe (or other GM full size truck)?

I honestly know next to nothing about the layout of Chevy engines (I'm an Acura/Honda guy myself)...I'm sure someone else can chip in as far as where the vacuum line is located.

Well, that's fine. I've got an Accord (2001) that I want to do this as well, but I'm afraid of screwing something up. Where is the line on the Accord?

Find the brake booster (big, round usually black and has the master cylinder and reservior on it) on the firewall. There will be a fairly good size vacuum line coming off of it (usually about 1/2" diameter). You pull that vacuum line off of the booster and slowly trickle the seafoam down it.

If I were you, I would look in your owners manual to locate the master cylinder. The brake booster is the thing the cylinder is mounted to on the firewall, as the poster above states. You don't want to go pouring this stuff down the wrong lines. If you pour it into a brake line or a heater hose, I am sure bad things could happen.

Inspired by this topic, I grabbed a can of Seafoam earlier today when I was at the shop. My only problem now, is that I know too little about my truck to know where the brake booster line is. I have a 2000 sonoma...can anyone point me in the right direction?

Typically, the brake booster is fairly easy to spot on the driver side of the firewall. The vacuum line usually is attached to the upper left portion of the booster and held on with a frustration-clamp(tm) (the kind of hose clamp that's only bent wire and really difficult to dislodge). The vacuum line should lead directly into the intake manifold and be fairly easy to trace back as such. If I had a digicam on me, I'd post a pic of the booster and vacuum line on my '85 ramcharger...

OK, I put what I thought was a third of the bottle through the BBL, turned the engine off, waited a few minutes, then started up. No smoke, or at least, none that I could make out at dusk. I drove around a few minutes, raced the engine a little, and still didn't have smoke. Either the intake is clean (unlikely after 68K) or I didn't do it right. Perhaps not enough additive? Did I not wait long enough?

i wait about 15-20 minutes before cranking her back up again.

on my maxima, the bbl comes from a round black circular thing on the driver's side firewall. there is only one tube that comes out of it. it has a vacuum, so you'll feel it sucking. Let the engine's vacuum "sip" the seafoam until it's in there, w/o letting the engine die. then let it sit for 15, crank her up, and you should see some smoke. it's mostly just the seafoam burning off, but it does help. i have a video of my cloud on my other computer, but it's not hooked up.

g'luck.

I dumped a can of seafoam in my gas tank yesterday. I will also buy another can to put in the BBL, once I get a solid idea of which line it is.

IM on the fence about this stuff. Ive used it, and it seems to make it run a little better, but there is not an increase on mileage. Id like to see someone take a peek in an engine, THEN put it in and see if itcleans anything. I know it doesnt do jack on a small engine (lawnmower) because i did this exact thing. Im not sure if buildup is less severe in a car engine.

While I will agree that this is some good stuff, Seafoam does not clean the intake. Neither will a carb cleaner, or any other such thing that claims it does. To "clean" the intake, you have to take it off & clean it by hand, be that with a brush, or a rotary cleaning tool.

Will seafoam make your car run better? Yes probably, mostly due to oil residue/buildup in the intake manifold and throttle body, and other parts attached to it (idle control etc). I think its a good product to use, but you do the booster trick, remove the intake and it will look the same as if it were not done.

I see many of my fellow shop owners sell these kinds of 'induction services' etc. Its all a sham to make money. Spraying some throttle body cleaner inside the TB of customers cars does indeed help things run better/smoother, but I will promise that its not 'cleaning the intake'.

Also, remember that some GM Vehicles have Hydroboost, so there may not be a vacuum Line going to the intake manifold.

To the original poster, your tahoe may be due for a tune up, (AC Delco plugs, Wires, Fuel Filter, Air Filter, clean Mass Air sensor etc) to get the mileage back up to snuff. Remember the ethanol blends, and also, depending where you are, the winterized fuel during 'colder' months. Also check tire pressure, alignment etc to make sure you're optimizing the efficiency of the vehicle. Are you hauling around stuff you dont need?

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"shop owner"

'nuff said!

i don't know much about cars and stuff, but I know my diesel is getting horrible mileage here in Amarillo. I have been here two weeks and it is about ten mpg pulling an empty trailer

quote:

---

Gas Pumping Tips:

Gas pumps pump both gas and vapor, you pay for both.
-So fill your tank on the slowest setting the handle offers to keep
the vapor production while filling at a minimum.
-Every pump has a vapor return in the hose. The more vapor that
you pump in while filling there is, the more that goes back into the
hose. Meaning the more you pay for nothing! Boo!
-Each handle should have three locking settings, choose the low one,
the one that pumps the gas the slowest.
-No need to pay to pump vapor that goes right back into the hose.

---

Most pumps designed for liquid won't pump gases. Filling up on the lowest setting will do nothing but piss off everyone around you.