Fuel additive after fillup

[Digital2k2]

A lot of fuel system cleaners instruct to add them to a near empty tank and then refuel with up to xx gallons.

Does anyone see where it would make much difference in adding it once your fuel level is down to the amount you want to treat?

Seems like it'd mix in just as well after driving around a bit...

 

[Bluestream]

Some tank have a fuel filler hose that has a low point. Some of The treatment can get stuck in the hose if you put in in last.

 

[bigmike]

I toss it in either way. However, I did that once on the Honda and it wouldn't start. It cranked up after the 3rd try and I figured it must have sucked in the cleaner first.

 

[salesrep]

Some do require agitation, best to add it first.

 

[Jimmy9190]

When you put the additive in the tank first then fill with fuel, the action of the fuel being pumped into the tank mixes the fuel much better than when you put additive into an already full tank.

 

[CharBaby]

Originally Posted By: Jimmy9190
When you put the additive in the tank first then fill with fuel, the action of the fuel being pumped into the tank mixes the fuel much better than when you put additive into an already full tank.


In addition to this, many gas tanks have a check valve at the top of the tank where the fill tube enters. This check valve is spring loaded and only the force of fuel being pumped is strong enough to open the valve. If you pour in the additive after filling the tank, the additive may just sit there in the fill tube and if the additive does get mixed in with the fuel, it will be veeeery slooooowly. Only seeping in where it may do little and could be money and additive wasted.

 

[rslifkin]

Adding the additive first mixes better. If you add the additive after, take the car for a drive immediately for 5 - 10 minutes to slosh the fuel around and mix it up.

 

[TaterSalad]

I've always pumped about a third of a tank of gas first, then the additive, then fill the gas.

 

[Digital2k2]

I hadn't thought about all the additive possibly not even getting into the tank, hmm...

Might have to give up tracking gas mileage during the treatment. My tank's larger than what it'll treat, so I can't fill it up if I add it before pumping.

 

[raytseng]

As long as your tank isn't completely full, just go to the station to add your additive. Top-off or fill your tank to wash it down.

It may have slipped your mind but you don't have to wait for an empty tank to get gas, nor do you have to always fill a tank up to full.

Even if you just chase it with half a gallon of gas, that's still a lot of fluid, and plenty to get the additive into the tank.

 

[raytseng]

Originally Posted By: Char Baby

In addition to this, many gas tanks have a check valve at the top of the tank where the fill tube enters. This check valve is spring loaded and only the force of fuel being pumped is strong enough to open the valve. If you pour in the additive after filling the tank, the additive may just sit there in the fill tube and if the additive does get mixed in with the fuel, it will be veeeery slooooowly. Only seeping in where it may do little and could be money and additive wasted.


Quesitonable,
If this were true, if I run out of gas, and have to add gas from an portable fuel can, then the fuel will just spill out over the top and won't get to the tank? That does't happen in "many gas tanks" in my experience

 

[rslifkin]

Many do have a flapper at the top of the fill tube, but that can be held open by inserting a long funnel. Some do have a rollover valve (check valve) near the tank, but it's only triggered to close if you flip the vehicle over.

 

[Digital2k2]

Originally Posted By: raytseng
As long as your tank isn't completely full, just go to the station to add your additive. Top-off or fill your tank to wash it down.

It may have slipped your mind but you don't have to wait for an empty tank to get gas, nor do you have to always fill a tank up to full.

Even if you just chase it with half a gallon of gas, that's still a lot of fluid, and plenty to get the additive into the tank.


See the only reason I'd add it xxx miles after pumping is because my tank's capacity is lager than what the additive will treat. I may be a little crazy or just have OCD because I can hardly stand not tracking my gas mileage haha.

Maybe the best thing to do would be to buy two bottles and figure out exactly how much I need to add to treat my tank. That way I can put it in before filling up and still track my gas mileage.

 

[salesrep]

Dear ocd ,

1)Buy a gallon or 2 measure the exact amount needed into smaller bottles and treat away.
2)But an additive that comes in the size you need to treat your tank.
3)Chill, pour, and drive. A Little more or less will make a minuscule difference