Motoring Discussion > Why run your tank to nearly empty? Miscellaneous
Thread Author: L'escargot Replies: 70

 Why run your tank to nearly empty? - L'escargot
I fill up when my tank is down to about half. Each fill-up costs less, there's no chance of me ever running out, I can always fill up with my preferred brand, and I can be more selective about choosing a low price petrol station.
 Why run your tank to nearly empty? - movilogo
I fill up when warning light is lit. Usually I can still get ~50 miles there after.

Advantage:

Still time to choose a cheaper pump
Less frequent to top up (compared to frequency of top ups at half filled tank)
Easy to measure fuel economy
Car carries less weight so better fuel economy ;-)

It also depends how big is your tank. Mine is just 38 L. So, I don't bother filling up unless it is near empty (exception when going on long journey (200+ miles) I always start from home with full tank).

 Why run your tank to nearly empty? - Oldgit
Now, just how many cars is it that the main motoring organisations have to bail out every year because those silly people run out of petrol - quite a few, I know.
Of course, rightly, they make an additional charge for this service, which should be totally unnecessary but unfortunately due to people's stupidity, is a fact of life.

I fill up when my tank approaches about a third full and would never let it get to the sort of level that existed when I picked up my car, from new, last July, when the dealer generously gave me enough petrol for about 50 miles.

Will people ever learn that it is not clever or wise to nearly run their tanks 'dry'?
 Why run your tank to nearly empty? - CGNorwich
What a sensible lot you all are. I never fill up until the last moment and even when running on empty impose rules on myself: Never go into a fuel station on the "wrong" side of the road;, never use a supermarket; never enter a station with queues. Haven't run out yet but have come very close.
 Why run your tank to nearly empty? - Dog
I'm going back a few years but - my BiL used to only buy petrol for his J4 van by the gallon,
that is to say - he never had more than 1 gallon in the damn thing at any one time!
He was always skint, but when he did have a few bob it would go to the bookies or the boozer :)
 Why run your tank to nearly empty? - BobbyG
I always wait to the light comes on and fill the tank, easier to check mpg and less trips to the petrol station.

I have asked this time and time again, where is the evidence that running your tank low is bad for your engine? Why would all this supposed nasty stuff get through when it wouldn't normally get through filters?

Where does the fuel come out the tank? At the bottom, just up from the bottom or where?
 Why run your tank to nearly empty? - Zero
>> I fill up when my tank is down to about half. Each fill-up costs less
>> there's no chance of me ever running out I can always fill up with my
>> preferred brand and I can be more selective about choosing a low price petrol station.

And (assuming your tank is 50 litres) you are always carrying a minimum of 18kgs of weight around with you.

The each fillup costs less is a good one! you use as much petrol and pay as much as you need to travel. Why not stay at home? would cost even less then.

Last edited by: Zero on Mon 26 Apr 10 at 09:08
 Why run your tank to nearly empty? - L'escargot
>> The each fillup costs less is a good one!

The cost is less of a shock, and I don't need to have as much reserve in my wallet or bank account.
 Why run your tank to nearly empty? - kensitas
Not sure why there's such an emphasis on the full/empty/half-full marks.

I rarely fill my tank completely these days (unless I'm going more than 200-300 miles in one shot) so usually fill to three quarters & rarely let it get below one quarter full.

I'm in the same 'position' as L'es, but am always carrying much less weight, but can still pick & choose where I buy without the panic stations of an glowing no fuel light.

My range (on my average fuel consumption) using this strategy is about 290 miles.
 Why run your tank to nearly empty? - lancara
Isn't there a theory (urban myth?) that you should fill up when your gas tank is half-full (or half-empty) because the more petrol you have in your tank the less air there is and petrol evaporates rapidly, especially when it’s warm. Similarly, fill up in the morning as temperatures are lower and fuels are denser.
 Why run your tank to nearly empty? - Oldgit
Isn't there anothe truth or is it myth that running out of petrol, thus causing the engine to splutter or backfire etc. damages the catalytic converter? If that is so, then that alone, apart from the inconvenience, is a reason for keeping reasonable amounts of petrol in your tank.
 Why run your tank to nearly empty? - FotheringtonTomas
>> the more petrol you have in your tank the less air there is and petrol evaporates rapidly

There could well be an "urban myth" re such.

>> Similarly fill up in the morning as temperatures are lower and fuels are denser.

Ditto.
 Why run your tank to nearly empty? - hawkeye
>> I fill up when my tank is down to about half.

So do I after the terminal embarrassment of running out of diesel yards from the petrol station.

But the trip computer said I had another few miles left ...

And other feeble excuses.
 Why run your tank to nearly empty? - ....
The difference in kerb weight in my car between quarter of a tank and full is just under 40kgs or just over 2.5%. If this has a direct impact on my fuel consumption then I would burn an extra 10 gallons or two thirds of a tank of fuel over the year carrying the extra weight.
 Why run your tank to nearly empty? - RattleandSmoke
I just wait till I run out of fuel and then cycle the car back home before trying to find a car without a locking filler cap to get some new fuel :p

In all serious though I don't like to drive round with too much fuel in the back and there are thouands of petrol stations so its not a problem. When you're driving a car which is averaging 28mpg filling up hurts.
 Why run your tank to nearly empty? - Dr_Rubber
I used to fill my TDI up at 1/2 full as I like to have a reserve in case I need to go somewhere in a hurry (or more likely forget to fill up before an early morning jaunt to the airport). However, my new HDI has a FAP system that tops up the tank with expensive ELOSYS (sp?) everytime you pop the fuel flap. With this I understand it is best to go full to empty as it minimises ELOSYS use.
FWIW, mine has 10l left in the tank when the light comes on - good for 100 miles!
Joe
 Why run your tank to nearly empty? - Dave_
I begrudge having more than £15-£20 worth in the tank in case the car expires - it's on its last legs and I need every penny. I frequently run it until the fuel needle doesn't even climb up to the Empty mark.
Last edited by: Dave_TD {P} on Mon 26 Apr 10 at 12:29
 Why run your tank to nearly empty? - seaside
Clearly some people don't mind spending more time in petrol stations than they need to; for me the fewer the visits the better, so I'm a full tank to "low fuel light on" man. This still gives me 50 miles or so to find fuel. In over 500,000 miles of motoring, I've never run out of fuel.
 Why run your tank to nearly empty? - RattleandSmoke
My dads mentallility exactly. Why have £50 worth of fuel in the tank when the car is only worth £300.

I was very annoyed filling my Corsa up for the last time as the petrol station had a £5 mininum spend, I had to put £5 of fuel into a car I knew the head gasket had gone on.
 Why run your tank to nearly empty? - crocks
Put in £2 worth. Go to kiosk. Offer £2 cash. Tell them that is all you have. They won't turn down your money.
 Why run your tank to nearly empty? - RattleandSmoke
But all I had on me was a five pound note!!

 Why run your tank to nearly empty? - crocks
Serves you right for being so flushed!
 Why run your tank to nearly empty? - Duncan
>>>> HDI has a FAP system that tops up the tank with expensive ELOSYS (sp?) everytime
>> you pop the fuel flap. With this I understand it is best to go full
>> to empty as it minimises ELOSYS use.

Woss ELOSYS Joe? FAP too for that matter?
 Why run your tank to nearly empty? - Dr_Rubber
>>
>> Woss ELOSYS Joe? FAP too for that matter?
>>

FAP is name Citroen give the diesel particle filter system fitted to their cars.
ELOSYS (I'm sure I'm spelling it wrong) is the additive required to make the FAP work.
All IIRC of course :-)
Joe
 Why run your tank to nearly empty? - L'escargot
>> there are thouands of petrol stations so its not a problem.

Not in our neck of the backwoods.
Last edited by: L'escargot on Mon 26 Apr 10 at 14:53
 Why run your tank to nearly empty? - madf
I buy diesel - Shell - where it is cheapest - about 3p per litre vs anywhere else.
SO I run the tank down to one bar left - about 7 litres and refill with 30 odd litres.

Hence lowest fuel costs and minimal journeys to fill up.
Simples.
 Why run your tank to nearly empty? - R.P.
Got into the habit during the fuel blockades of topping up whenever. Tend to run the tank down now and fill up in a Shell garage for the same reasons as madf.
 Why run your tank to nearly empty? - scousehonda
Surely these days it is more economical to fill up as often as possible as, certainly around here anyway, fuel is going up by at least 1p per litre per day. Better to put 30 litres in today at 120p per litre than put 50 litres in tomorrow at 121p per litre.
 Why run your tank to nearly empty? - RattleandSmoke
I tend to use Esso (Tesco) or Shell because they are the cheapest. I avoid the Texaco station because its very run down and have heared too many horror stories.

I only ever pay cash in petrol stations now anyway.
 Why run your tank to nearly empty? - crocks
Whenever I fill up Tesco start a "5p/litre off with £50 spend" promotion the next day. :-(
 Why run your tank to nearly empty? - WillDeBeest
I view the car as a trusted tool, rather than an ornament or a cosseted pet. Filling up halfway through a tank would take me into the pits with 300 miles - three hundred miles! - in hand. That would be simply daft.

I have a long drive to and from work (170 miles a day). Fuel is significantly cheaper in my part of Warwickshire than anywhere else I go, so I do occasionally nurse the car home on an eggcupful rather than stop to fill up at home counties prices. Even with the Feed Me light well alight, I've never managed to fit more than 63 litres into the 70-litre tank.

This, to me, seems like no more than using the car as it was designed (superbly, I think) to be used. There's a young lady at the greengrocers with a smile that can make my week; there's no-one like her at the petrol station, so I go there only when I have to.
};---)
 Why run your tank to nearly empty? - FotheringtonTomas
It's more economical on normal run-around journeys (less so on long motorway runs).


>> there's no chance of me ever running out

I look at the fuel gague to see when to fill up.


>> I can always fill up with my preferred brand

Makes no difference to me, although I avoid supermarkets - not because of fuel concerns, just because I like to support other businesses.


>> and I can be more selective about choosing a low price petrol station.

I normally pass quite a few in my normal weekly travel. I also subscribe to that fuel price newsletter thing run by B. McLoughlin (PetrolPrices.com). My cheapest "local" unleaded ordinary petrol is £1.21p/litre, the dearest is £1.29p. That without getting off my chair!
 Why run your tank to nearly empty? - Runfer D'Hills
I just treat the quarter full mark as empty and re-fill to 1st click. I prefer things you don't have to worry or think about much.
 Why run your tank to nearly empty? - Fursty Ferret
I know I can get about 50 miles past the "0" range mark on the trip computer. Never dared take it further. Why?

1. The fewer times I have to fill up, the less I worry about what it costs me.
2. I can get 750 miles to a tank so I only visit the petrol station once a month.
3. The bottom of the tank doesn't fill with sediment (or if it did, it doesn't any more).
4. I like to live life on the edge.
5. If I lend the car to someone else, they panic at the sight of the fuel light and fill it up for me.
 Why run your tank to nearly empty? - DP
I fill up to the brim, and refill when the light comes on. Reasons are:

1) I don't see the point in filling the tank any more frequently than I have to.

2) Low fuel light on both cars gives at least 50 miles remaining range.

3) I always zero the trip meter on refilling as a backup to the fuel gauge, and know what both cars will do on a tankful.

4) Why carry all that weight around unnecessarily?

If I'm doing a long journey and the car has, say a quarter of a tank left, I will refill it to save stopping the next day, but otherwise I just drive to the light.
 Why run your tank to nearly empty? - Avant
Agree with DP. One of the reasons for having a diesel is that you only have to fill up every 500 miles or so (a bit less if I've been in town a lot, quite a lot more on long runs).

Better for my waistline too - when filling up the car's tank it's too tempting to fill my own with a little snack.
 Why run your tank to nearly empty? - Bellboy
interesting thread
absolutely everyone has failed to grasp that most modern fuel pumps are in the tank and need the fuel petrol or diesel to stay running cool
if you repeatedly run your car to nothing you are stressing these pumps
pumps cost money,big money
i never understand the mentality of running cars on fumes
 Why run your tank to nearly empty? - Dave_
>> the Feed Me light

or, as I heard it called the other day, The Lamp Of Many Footsteps.
 Why run your tank to nearly empty? - WillDeBeest
Hardly fumes, BB. Most of us have merely taken issue with the Helix's idea of filling up at halfway. Surely no pump needs that much cooling.
My Volvo diesel pump has had seven years of typically 55-litre fills (into a 70-litre tank, remember) and is still running well as it approaches 110,000 miles.
 Why run your tank to nearly empty? - L'escargot
>> Most of us have merely taken issue with the Helix's idea of
>> filling up at halfway.

The question was "Why run your tank to nearly empty?" I was merely interested in getting an insight into why some people run their tank to nearly empty. It appears that stating my own filling practice has clouded the issue and has become a major part of the discussion.
Last edited by: L'escargot on Tue 27 Apr 10 at 08:16
 Why run your tank to nearly empty? - Old Navy
I fill the car every Thursday, (our weekly shop day), it usually requires between half and three quartrers of a tank. Or when the tank is quarter full if sooner, caused by pensioner long distance roaming.
 Why run your tank to nearly empty? - Zero
>> The question was "Why run your tank to nearly empty?" I was merely interested in
>> getting an insight into why some people run their tank to nearly empty.

Basically because there is no good reason not to, and when you do a lot of miles its inconvenient to keep stopping to fill it up.

>It appears that stating my own filling practice has clouded the issue and has become a >major part of the discussion.

Indeed, mostly because it appears to some of us as slightly bizarre.

If you didnt keep luggin half a tank fo fuel around with you all the time you would improve your fuel consumption. Now I know you have records going back to the year dot with each litre of fuel bought, so why not try it as an experiment and let us know. Who knows, with your immaculate record keeping you might be able to make us change our ( to us) normal habits.
 Why run your tank to nearly empty? - L'escargot
>> Indeed mostly because it appears to some of us as slightly bizarre.

I'd sooner be the butt of derisive comments, and be seen as bizarre, rather than just being ignored! Bring it on!
:-D
 Why run your tank to nearly empty? - Zero
dont get carried away, its only slightly bizzare.
 Why run your tank to nearly empty? - Cliff Pope
Or bizarre even.
 Why run your tank to nearly empty? - Clk Sec
I've not seen a pedant around for ages.

Clk Sec
 Why run your tank to nearly empty? - Zero
no i said only slightly. so its not quite bizarre
 Why run your tank to nearly empty? - L'escargot
>> dont get carried away its only slightly bizzare.
>>

Slightly is better than nothing!
:-D
 Why run your tank to nearly empty? - WillDeBeest
I've not seen a pedant around for ages.

No, these days we mostly rely on cameras and databases. It's why there's so little enforcement of apostrophe misuse out there.
 Why run your tank to nearly empty? - Pat
There's far better things to misuse than apostrophe's or that may be apostrophiii :)

Pat
 Why run your tank to nearly empty? - seaside
I think you'll find that there's no apostrophe in apostrophes.
 Why run your tank to nearly empty? - Oldgit
>> I think you'll find that there's no apostrophe in apostrophes.
>>

There might be in 'apostrophe's misuse' or maybe not.
 Why run your tank to nearly empty? - Clk Sec
There used to be some quite lively pedantic discussions on the other side.
 Why run your tank to nearly empty? - Zero
And that is where we hope they stay. Pedanism is not tolerated here.
Last edited by: Zero on Tue 27 Apr 10 at 15:28
 Why run your tank to nearly empty? - Crankcase
Pedanism? No tea for you Zero?

 Why run your tank to nearly empty? - Oldgit
>> Pedanism? No tea for you Zero?
>>
>>
>>
Pedanism. That sounds like a perversion!
 Why run your tank to nearly empty? - Clk Sec
>>Pedanism is not tolerated here.

Methinks that's a wind-up.
 Why run your tank to nearly empty? - madf
Pedanism is what you get when your empty tank runs out.

A walk on your pedes..




I'll get my coat...
 Why run your tank to nearly empty? - Clk Sec
>>I'll get my coat...

And yer boots...
 Why run your tank to nearly empty? - CGNorwich
58 posts on when to fill up your tank! I think a little pedantry would make an interesting diversion. ( By the way shouldn't the title be "Why run your car until its tank is nearly empty)? Unless of course Mr Snail is running a tank in which case probably wise if a little costly to keep it fuelled :-)
 Why run your tank to nearly empty? - Crankcase
>> 58 posts on when to fill up your tank! I think a little pedantry would
>> make an interesting diversion.


In what way, exactly?
 Why run your tank to nearly empty? - L'escargot
>> ( By the way shouldn't the title be "Why run your
>> car until its tank is nearly empty)?

There's not enough room in the title box for all of that, or I would have put that. Try it and see for yourself.
:-D
Last edited by: L'escargot on Wed 28 Apr 10 at 07:13
 Why run your tank to nearly empty? - Bazzabear
And you always carry around at least a half tank of petrol, with the extra weight and therefore fuel consumption that entails.

I fill to the brim, and run it till it's nearly empty. I've never run out of petrol, nor had a situation where I felt at risk of doing so. I don't see that's it's so complex a situation that I have to give myself 150 miles worth of leeway in order to not mess up.
 Why run your tank to nearly empty? - rtj70
I would normally fill-up at half tank but now I have another reason not to add times. A fuel-card for the company car (not expensed). I pay an agreed amount my mileage each month. If I use more I pay more the following month. Use less and I get money back.

So if it's a month when I have only done personal miles (mostly) then filling up just before pay day means I will pay next month a lot more. I get a refund the following month.

The other side of this is the personal/business miles is worked out pro-rata. So if I did mostly business this month and won't next month then if I fill up before pay day it does not affect me the same.

Throughout the year it works out of course. But someone I know was lazy getting expenses in for a few months (so they didn't take extra money) and then when he did they had to reduce salary by hundreds. He owed it of course but it was one month when he had to pay it all.
 Why run your tank to nearly empty? - Armel Coussine
Running on empty goes with the emptiness of the pockets in one's frayed old trousers. All those bits of Jeycloth, pebbles, bits of wood and straw and human DNA, grains of sand and globules of alien fluids that get into one's fuel tank and after swirling about on the bottom for a while are sucked through the outlet pipe and burst through the cheapo fuel filter to give the injectors a terminal smoker's cough (Ah! for the easily rectified carb jets of yore!) run in parallel with the state of our overdrafts, bumping along the bottom of the extra bit they give you without mentioning it and generating a toxic muddy wake of letters at 25 quid a pop and punitive interest rates quite surprising in these times...

Even the rich can't make any money out of cash these days, let alone people like me who haven't got any.
 Why run your tank to nearly empty? - Auntie Lockbrakes
I always get the jitters when the low fuel light comes on. Even though I calculate that "Yeah, got 6 or 7 litres left, that'll easily do me 50-ish miles", I invariably then run into 1) lots of fuel-sucking steep hills, or 2) in to the least densely-populated part of the country that I am in with no filling stations for 55 miles.... You can then watch the needle slide down to empty! Stress I don't need!!!

I did run out of diesel once on the autobahn in Germany, 2 miles short of a gas station after 70-odd miles without one (a very rural part of Germany near the Dutch border). Grrrr!

So, as soon as the gauge is down to a quarter full I'm happy to bail-out and tank-up. Only costs 60p/litre here anyway :-)
 Why run your tank to nearly empty? - L'escargot
>> Only costs 60p/litre here anyway :-)
>>

But how does the average wage/income in New Zealand compare with that of the UK, taking into consideration the cost of things other than petrol?
 Why run your tank to nearly empty? - L'escargot
>> And you always carry around at least a half tank of petrol with the extra
>> weight and therefore fuel consumption that entails.

The extra mass of half a tank of fuel will, in the main, only have an effect when you're accelerating. At a steady speed the effect of the extra mass will be much less. In point of fact, at a steady speed the extra mass may be beneficial in that it will reduce the ground clearance and possibly decrease the drag coefficient and the effective frontal area of the car, thereby reducing the aerodynamic drag force.
 Why run your tank to nearly empty? - Zero
>> The extra mass of half a tank of fuel will in the main only have
>> an effect when you're accelerating.

you told us you drive in a sprightly manner, so there will be plenty of this

In point of fact at a steady speed the extra mass
>> may be beneficial in that it will reduce the ground clearance and possibly decrease the
>> drag coefficient and the effective frontal area of the car thereby reducing the aerodynamic drag
>> force.

YOu may tho increase the downforce on the car (ground effect) which will increase fuel consumption.
Last edited by: Zero on Wed 28 Apr 10 at 09:20
 Why run your tank to nearly empty? - Bazzabear
>> >> And you always carry around at least a half tank of petrol with the
>> extra
>> >> weight and therefore fuel consumption that entails.
>>
>> The extra mass of half a tank of fuel will in the main only have
>> an effect when you're accelerating.

Hmm... Not sure I agree with that. In a perfect, frictionless system perhaps.
 Why run your tank to nearly empty? - WillDeBeest
Either way, the effect must be marginal bordering on negligible. I can't say I notice any blunting of performance even when I've just taken aboard 60 litres of diesel. Come to that, I only notice the effect of passengers if there are at least three and they're all adults.

Our flying friends care deeply about carrying no more fuel than the journey and the safety rules require, but it's a different calculation when you're burning fuel to lift fuel. In a car: true in principle? Yes. True enough to matter? I doubt it.
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