Seafoaming a half-full gas tank

**oksk89** · 01-08-2010 04:04 PM

I have a new bottle of seafoam and I plan on dumping it all into my gas tank because I've been getting terrible MPGs.. However, I have two concerns:

1) The tank is a little under half-full
2) The gas currently in the tank is 87 octane

I normally use Shell V-Power, but when I drove my car back home for break, I was out of gas and my dad filled it up with 87 octane.

Now, would it matter if I used all the seafoam right now? Or should I wait until the tank is near empty, pour in the seafoam at the gas station, and fill it with 93?

PS. I have an arbitrary question. I've noticed that when I use Shell's V-Power, my engine sounds more 'throaty' (in a good way) and the engine seems a bit more responsive. When my dad put in 87, the car seems a bit sluggish.. but that's usually when I just start the car and it's cold outside (Boston). So, I don't know whether the sluggishness is due to the gas or the weather. I remember it not being so sluggish in cold starts when I used 93 octane.. so I'm not sure.

Also, am I just hearing things with the 93? My friend claims it's just a placebo effect and that my engine doesn't sound any different at all, regardless of whether you fill it up with 87 or 93.

**a4mafia(Red)** · 01-08-2010 05:16 PM

there should be directions as to how much sea foam to how much gas. use them.
if you have to little gas the sea foam can eat away at your gas lines

as for octane, it shouldnt matter for sea foaming. but try not to use it again.

on a side note, when i sea foamed my car, in the intake was the most effective. the gas and oil didn't seem to do as much.

**LEGO** · 01-08-2010 05:52 PM

Intake, oil, and gas all serve different purposes. And yes, octane does matter. Even when you open up the little door where your gas cap is, it says use only 91 and above. You can mess up your engine using lower octane.

**somebody5788** · 01-08-2010 06:25 PM

Your car retards timing when you use lower octane fuel and in sever conditions can probably even pull boost (or happens due to pulling timing). So yes you will have less power on 87 since it was designed for higher octane.

Although you will not damage it from the lower fuel because the car compensates for it.

**blackhat** · 01-08-2010 07:24 PM

Wait wait wait.. I can fill 87 in my 1.8T? O_O

**Haenszel20v** · 01-08-2010 07:32 PM

Yes your car can sound much throatier with a better fuel. You should see how much "tighter" an engine sounds on an engine down with Elf124 in it compared to 93 pump gas. The audible difference is amazing.

**Calabria** · 01-08-2010 07:38 PM

I wouldnt put anything less than premium in my car. Youll also get better mpg and in the long run save $ with gas and if hopefully let your engine run a long/healthy life.

**Seerlah** · 01-09-2010 04:19 AM

I would place a bottle of octane booster (choose whatever brand you feel comfortable with) in the gas tank, before I do anything. That should bring your octane to at least 91, hopefully. I have never used Seafoam before, so I don't know how much fuel would need to be in the tank to perform that task. But directions should be on the bottle.

As for your gas consumption, there are other factors that go into it. The main components for bad gas mileage would be your 02 sensors and MAF (just because they are functioning, does not mean that they are in 100% working order. they should be changed every 100k). After that, it could be due to other variables, such as air filter not being clean, not running proper air pressure in your tires (the less psi, the less mpg), not too sure if the fuel filter plays that much of an important role (but should be changed periodically), exhaust leaks, vacuum leaks, etc. And last but not least, a little freind I like to call Mr. LeadFoot

.

Edit: Forgot to add that your gas mileage decreases in the winter, and short trips eat gas really quick.

**somebody5788** · 01-09-2010 05:25 AM

Originally Posted by blackhat

Wait wait wait.. I can fill 87 in my 1.8T? O_O

Can you? Yes

Should you? No

The car will compensate for it. You will lose HP and MPG. Why do it when in the long run your not saving any money and your not having as much fun doing it either.

**biketsai** · 01-09-2010 11:19 AM

Finish up this tank then right before you go to fill up, pour the seafoam in so it mixes in there nicely with the new tank. Please put some 93 in the car in the future.

**lucidor** · 01-09-2010 11:53 AM

I live in Cali and we only have 91

**calvin1.8t** · 01-09-2010 03:15 PM

Originally Posted by oksk89

I have a new bottle of seafoam and I plan on dumping it all into my gas tank because I've been getting terrible MPGs.. However, I have two concerns:

1) The tank is a little under half-full
2) The gas currently in the tank is 87 octane

I normally use Shell V-Power, but when I drove my car back home for break, I was out of gas and my dad filled it up with 87 octane.

Now, would it matter if I used all the seafoam right now? Or should I wait until the tank is near empty, pour in the seafoam at the gas station, and fill it with 93?

PS. I have an arbitrary question. I've noticed that when I use Shell's V-Power, my engine sounds more 'throaty' (in a good way) and the engine seems a bit more responsive. When my dad put in 87, the car seems a bit sluggish.. but that's usually when I just start the car and it's cold outside (Boston). So, I don't know whether the sluggishness is due to the gas or the weather. I remember it not being so sluggish in cold starts when I used 93 octane.. so I'm not sure.

Also, am I just hearing things with the 93? My friend claims it's just a placebo effect and that my engine doesn't sound any different at all, regardless of whether you fill it up with 87 or 93.

dont put in in on a half tank. only a full tank. its really powerful stuff and it works perfect with a full tank.