When to buy gas???

[njlou]

OK - I admire all of the fuel saving ideas posted, but you (most) still have to buy some gas. --- or alot!
Here's the question - it has been bugging me since the first gas shortage -1970's.
Here goes: Do you fill up your tank when nearly empty or nearly full. It sounds trivial almost a joke but it is a serious problem. Example- since the price is constantly going up you have to pay the new price on the whole tank, even though it was burned weeks ago. effectively you are paying for fuel retroactively at the new price. If you have an empty tank after a few days or weeks the price may change dramatically on the day you buy it and also in between. so you are paying for all gallons used at the higher price.
lets say that you filled up at $2.75. A month later you are empty and you need to fill up at $3.25. So your 20 gallon fill is $65 vs $55. BUT maybe you should have filled up att 1/2 tank at $3.00 x10G= $30 + $3.25x10G=32.5 = $62.5 vs $65. so when the prices are going up you MAY save by filling more often. It's calculator time.

[Arminius]

I just wait until the tank is empty.

http://www.gasbuddy.com/

[AndrewJ]

I buy gas when the needle points to "E"

I know people who like to get caught up in the whole "fill up before the price goes up" schtick, but there's no way of predicting future prices.

The law of averages makes sure it all evens out in the end.

[Compaq888]

Originally Posted by AndrewJ

I buy gas when the needle points to "E"

I know people who like to get caught up in the whole "fill up before the price goes up" schtick, but there's no way of predicting future prices.

The law of averages makes sure it all evens out in the end.

ditto

[Doofus McFancypants]

The math may work out ( assuming gas prices do not come back down) but in the long run - it is probably even.

I try to shoot for about 1/4 tank - although i am tempted to run it dry just to see how many miles i could actually go....

Kinda related ( at least WRT Fuel Proces) Depending on where you live - there may be some stores that offer $$ off gas.
I have a Kroger near by - ever $100 in groceries you spend - you get $.10 off per gallon.
with the 2 kids - we easily cross $200 - gives my wife and I at least 1 tank with a discount.
I know BJ's and Costco also have discounted gas - depending on the miles you drive - the gas savings could even cover the membership costs at those places.

Steve

[njlou]

Now a new question. When will oil hit $100/ BBL - LOL

We need a mega Boycott!! not for a day but for a month. Dont buy Exxon for 1 month.The rest of this month and all May stay away. buy all you want elsewhere but not Exxon. Also NEVER BUY CITGO> It comes from Venezuela and they are not friendly.
Next Month (June) stay away from Lukoil and sunoco. Unfortunately you cannot feel sorry for your local retailer. Pressure on him will make it work.

[Lazarus]

Originally Posted by njlou

Now a new question. When will oil hit $100/ BBL - LOL

We need a mega Boycott!! not for a day but for a month. Dont buy Exxon for 1 month.The rest of this month and all May stay away. buy all you want elsewhere but not Exxon. Also NEVER BUY CITGO> It comes from Venezuela and they are not friendly.
Next Month (June) stay away from Lukoil and sunoco. Unfortunately you cannot feel sorry for your local retailer. Pressure on him will make it work.

To help with your decision.

Boycotts won't work unless you are using less fuel just shifting around to different stations will not change anything.

Welcome to the site!

[cfg83]

Frank -

Originally Posted by Frank Lee

The best time to fill is when it has 1/4 tank or less. Your calculation isn't taking into account all the extra screwing around at gas stations for small fills.

This is what I do. I fill from 1/4 to 3/4, which is what I used to do prior to being an MPG junkie. I *know* from experience that this is about 5.5 gallons for my gas tank. I never state my single tank fill-ups when talking about MPG. I only go by my 90-day average, which is based on GPS-corrected odometer readings and what the gas station reports in gallons. I am susceptible to pump-error, but I think it evens out over 90 days. The drawback to this is that I can't prove "the little mods" based on my system, .

CarloSW2

[awillard69]

If you are worried about economy and hedging the price of gas, figure out how many gallons you need for a reasonable period, say 5 or 8 gallons for a weeks driving. Then, when you get below 1/4 or when your "Hey stupid, you need gas!" light comes on, put in those gallons you really need.

If you put in 20+ gallons and gas weighs about 6.5 pounds per gallon, you are totting around an extra 120+ pounds. Somewhere there's a calculation about how much dead weight costs you in economy, something like 1-2% MPG for each 100 pounds you eliminate.

So, not filling up will save you weight and therefore extend your distance between stops at the gas station. You will still dollar cost average expenditures. And you could fudge it a bit more or less when the gas price slightly dips or spikes.

[Arminius]

Post of the Day!

Originally Posted by awillard69

If you are worried about economy and hedging the price of gas, figure out how many gallons you need for a reasonable period, say 5 or 8 gallons for a weeks driving. Then, when you get below 1/4 or when your "Hey stupid, you need gas!" light comes on, put in those gallons you really need.

If you put in 20+ gallons and gas weighs about 6.5 pounds per gallon, you are totting around an extra 120+ pounds. Somewhere there's a calculation about how much dead weight costs you in economy, something like 1-2% MPG for each 100 pounds you eliminate.

So, not filling up will save you weight and therefore extend your distance between stops at the gas station. You will still dollar cost average expenditures. And you could fudge it a bit more or less when the gas price slightly dips or spikes.

[igo]

I won't start thinking about gas until I am under the 1/4 mark. If I come across a cheap gas station and I am under the 1/4 mark I will typically fill. I like to run my tank low so I carry less weight.

[RH77]

I try to buy gas when I'm nearly empty. This way, the margin of error on short-fills is eliminated for a more accurate FE picture.

The exception: before driving holidays (Labor day weekend, 4th of July, etc.) and ozone alert days.

Speaking of Ozone, the more you fill, the more you expose the atmosphere to gasoline vapors, contributing to the problem (even with the vehicle's on-board, and the pump's vapor recovery systems).

RH77

[LostCause]

The longer you can go without gas, the wiser it is to fill up at once. Currently, I only buy gas every 3.5 to 4 weeks. Utilizing two 15 gallon Jerry Cans, that could probably safely be brought up to 12 weeks. It's common knowledge that gas degrades over time, but I think it would be fine if kept in an airtight container located in a cool spot. There are probably other cheap/free techniques in stabilizing gas that could be utilized without negating potential savings.

If you can hold out 12 weeks, you can easily get through the summer driving season. The summer driving season is always more expensive than any other season, so there wouldn't be much price guessing. You do have to deal with 30 gallons of highly flammable gas near your house and the risk of losing meager savings due to evaporation/degradation.

Personally, I just buy gas when I'm on empty at the cheapest station along my commute.

- LostCause

[trikkonceptz]

Once I get my Scanguage I'llplay with this some more, but before I got real serious in trying to improve my MPG's I noticed that switching between gas stations tanked my MPG's, it all stabilized once I selected a particular Gas station, BP in this case because they are Canadian Sourced, but then I noticed a diffference in MPG's depending on time of day fill ups too.

Therefore now I fill up mornings only, from the same station and my MPG's are climbing on those factors alone ... Now as I start applying some techniques I see here I should be well above EPA in no time .. 40mpg here I come ...

[roflwaffle]

Originally Posted by Frank Lee

The best time to fill is when it has 1/4 tank or less. Your calculation isn't taking into account all the extra screwing around at gas stations for small fills.

And asses looking for fuller tanks to siphon.

[LUVMY02CREW]

I usually try to wait till 1/2 or less, with erratic fuel gauge I don't want to risk running out. I don't really try to guess when gas may go up/down, cause I'm gonna need it regardless of the price on any particular day.

After dropping off 2 of my kiddos at their schools, I commute to work and still have some time left over. This is when I fill up: in the mornings, same station, I even try to get the same pump if possible, same octane, etc... I try to keep it same to help eliminate any possible variables when filling up.

I also try to top off each tank, all the way up so I can see the gas at the flapper thingy in the filler hole. This way I know I have a FULL tank. I have noticed that even at the slowest notch on the handle, that the remaing amount I can squeeze in can vary from 1 to 2.5 gallons.

So.... I guess my new questions related to fillups are...
1 - Is topping off a good/safe thing to do to keep an accurate record of fuel used?
2 - Are there alternatives to topping off to be accurate?
3 - Would there be be any possible safety/mechanical/other drawbacks to topping off?
4 - Any other questions somebody else might have........?


I know gas pump police put the warning on the handles to try and keep me from doing this, but I guess I'm just a little rebelious sometimes



p.s. And, to expand on what Frank said about screwing around at the gas station more times, more stops give me more chances of buying that extra gatorade and snickers that I know I could do without

[metroschultz]

Originally Posted by LUVMY02CREW

....This is when I fill up: in the mornings, same station, I even try to get the same pump if possible, same octane, etc... I try to keep it same to help eliminate any possible variables when filling up.

I also try to top off each tank, all the way up so I can see the gas at the flapper thingy in the filler hole. This way I know I have a FULL tank. I have noticed that even at the slowest notch on the handle, that the remaing amount I can squeeze in can vary from 1 to 2.5 gallons.
So.... I guess my new questions related to fillips are...
1 - Is topping off a good/safe thing to do to keep an accurate record of fuel used?
2 - Are there alternatives to topping off to be accurate?
3 - Would there be be any possible safety/mechanical/other drawbacks to topping off?
4 - Any other questions somebody else might have........?
...........

Topping your tank to the fill flap is BAD.
It is neither good nor safe.
There is a designated expansion space in the upper portion of the tank that you are trying to fill with fuel.
This is why you see a variable from "1 to 2.5 gallons"
Eventually all this extra raw gas ends up in your carbon canister.
You can't just clean them any more like on the old cars.
If your canister becomes too contaminated for the system to self clean it has to be replaced, and on your 02 Crew that would be in the $300 to $400 range.

You say you always use the same pump( or try to anyway)
Pick one ring of the spring around the end and use that spot always,(that spring is there to keep the nozzle from pulling out anyway).
Then when it cuts off by itself you will have a very good fill to the same level every time.
When you use this method you may even see an increase in your MPG.

Do not under any circumstances keep pumping till you can see gas in the neck.
BAD JOOJOO
The raw gas stored in the canister is supposed to go into the intake, but, sometimes during cleaning mode it will go in while you are in the highway and the mix will be heavier than stoichiometric.
some cars will make it as rich as 10/1.The car is trying to use engine vacuum to get rid of that extra gas.
This is extremely wasteful.
The other problem you can run into when "Gas Packing" (the official term for filling into the expansion space).
You fill in the am. Fuel is cool and therefore more dense.(I know it is minor, hang on I'm making a point)
You don't drive very far. You park on an incline, nose up.
In the afternoon sun this extra gas expands.
You come out to your car to see a puddle of raw gas on the ground coming from the neck.
This I have also seen in my days at the local garage.
I hope this helps.
Schultz.

[RH77]

1. Others can probably attest to this better, but you may be filling both the tank and the filler neck. The most accurate is the same fill every time.

2. I set it on slow and take the first click (more on why in a moment)...

3. #1 drawback is evaporative pollution (ozone). The fumes evaporate into the atmosphere to create this unhealthy pollutant. Secondly, your truck's check engine light may come on. It happens now and then, but there's something to filling too much and freaking out the on-board vapor recovery system and/or return line from the fuel injection rail.

4. Not much else -- just consistency is key to getting an accurate number.

1 - Is topping off a good/safe thing to do to keep an accurate record of fuel used?
2 - Are there alternatives to topping off to be accurate?
3 - Would there be be any possible safety/mechanical/other drawbacks to topping off?
4 - Any other questions somebody else might have........?

RH77

[extragoode]

Originally Posted by metroschultz

Then when it cuts off by itself you will have a very good fill to the same level every time.

This is not entirely true. Due to the bend in the fill neck on my truck, even on the slow setting it will back up and click itself off after just a couple gallons have been pumped on a full fillup. Granted this is an exception as well as a fairly easy one to notice, but I don't count on it as being reliable.

Originally Posted by metroschultz

This is extremely wasteful.
The other problem you can run into when "Gas Packing" (the official term for filling into the expansion space).

[rant] "But how am I ever going to go 250-400 miles without stopping at another gas station?" says the average American, "Oh, wait, I'm an average American and only go 20 miles a day! Nevermind" Yeah right. [/rant]

[LUVMY02CREW]

Thanks for some good points to consider.

I'm not good yet at the whole quote and comment thing yet so I'll just make the comments then put the possibly new idea at the end.

- I hadn't thought about the expansion space issue, oops....but, my new idea may take care of this issue.
- I'll have to locate and inspect the charcoal canister for any degradation.
- No check engine light related to this so far, fingers crossed.
- "consistency is key to getting an accurate number" Thats what I've been shooting for and hopefully everybody else is also.
- I put about 60 to 70 miles a day on truck so I fill up at least once a week.

Now for my possibly new idea:

I got to thinking about the whole expansion area thing. What if I change my fill up location to before I make my commute(still fill to flapper for extreme accuracy)??? This way the commute will use up the "packed" in gas and the expansion area is there for the daily sun heatup.

Just thinking outloud on this, but theoretically seems reasonable this late at night