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Old 25th January 2013, 14:35   #16
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

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Originally Posted by ghodlur View Post
Venu sir,
I still use the tank ful to tankful method using the low fuel indicator as the reference point. I cant think of a situation when the indication comes up and the fuel in the tank can be more than the reserve fuel. If the fuel in the tank does not reach the reserve levels, the DTE will self correct and start reading more than 80 and the indication goes off. I have seen this happening. Pls clarify if my understanding is wrong.
I think you are right that the DTE corrects itself and keeps to above 80 reading when the fuel has not reached reserve. I don't usually go to that low a reading on my Fiesta, but I recently observed it on the Figo. When I started the car, it showed 90 kms on the DTE, and after driving for 22 kms, it showed 84. It was only on the return trip that it came below 80.

Coming back to the main topic, I agree with Karthikk that it does not make sense to fill Rs 500 fuel 5 times, instead of Rs 2500 in one go.
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Old 25th January 2013, 15:05   #17
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

Just to make a point, though I agree with the fact that one should go for maximum amount of filling every-time that one could, but if your vehicle is driven less, its better to go for smaller quantities.

This is because fuel 'loses' some of its burning capabilities if stored for long. This will no doubt in turn affect the performance of your car. Whether there will be any other damage to the engine is another point for discussion. Informed team members may like to enlighten us on this issue.

Regards.
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Old 25th January 2013, 16:02   #18
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

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Originally Posted by KarthikK View Post

It always beats me as to why many car owners don't simply tank up full everytime. It not only prevents cheating by bunk staff, but also lengthens the time between bunk visits. Instead of spending 500 Rs. 5 times, why not tank up for 2500 and prevent those 4 additional bunk visits? There is no extra money saved or lost with either method.
There could be multiple reasons for this.
- The person may not have Rs 2500 cash, and does not care about the existence of petrol on a future date.
- If someone uses the vehicle occasionally, he may consider the Rs 500 to the cost of that particular visit / day. He may not be comfortable shelling out 2500 at one go.
- There is a chance that fuel theft from a vehicle is rampant in a particular area which the car visits.
- Taxi drivers have cash constraints, hence they prefer filling up so that it lasts the day (till they get some money from the passengers)
- There is a chance someone else should be paying for the next fill (if vehicle is not used strictly for personal use)

But I have to agree that if a vehicle is used regularly, then doing a tankful makes sense. I believe majority of the self owned vehicles being used regularly do a tankful.
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Old 25th January 2013, 16:34   #19
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

So, can we conclude that there is no danger of dirt getting into the fuel system/engine due to running low on fuel (because of filters)? At the same time, damage may be caused due to lack of lubrication.
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Old 25th January 2013, 16:37   #20
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

I think, "don't run empty" logic holds good from two angles:
- Risk of air lock in fuel lines.
- Letting go of fuel in thin air (Vaporinzing!) - Of course, this may apply only for petrol.

From a slush point, it looks tricky from below:
- If slush formation is an unavoidable thing, manufacturers should have specified a tank cleaning procedure periodically.
- The nozzle that would draw petrol would have to fixed inside the tank (cant be floating on top level!). It has to be at bottom most so the dead storage is minimum. In that case, it could be drawing sludge anyways (esp when climbing up / down on inclines, hills, etc).

On the bi-fuel (CNG/LPG) cars, we may not have much choice wrt petrol, simply because tanking up petrol means, it would stay for months together (again, stale fuel!).
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Old 25th January 2013, 16:42   #21
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

Quote:
Originally Posted by vnabhi View Post
That is an inaccurate way of calculating FE. As you know, the warning light depends on the DTE reading, which itself varies from time to time, based on driving style and traffic. The real test is tankful-to-tankful.
Venu, isnt that a bit of contradictory statement? I mean when you say tankful-to-tankful and not waiting till Low Fuel Warning Lamp comes up?


Quote:
Originally Posted by vnabhi View Post
On the other hand, my son drives the Figo till the tank is nearly empty. I discovered recently that the Figo has 3 warning chimes associated with low fuel apart from the warning light--they come on when the DTE is 80, then at 40 and finally at 20. I've heard the chimes at a reading of 80 and 40, but never dared till 20 reading.
This is interesting. I think all cars should provide such 3-stage warning chimes which will be helpful for most youngsters or non-BHPians who wait till the car runs dry

Quote:
Originally Posted by ghodlur View Post
Fiesta does have a low fuel warning indication which appears when the DTE read 80 which means that assumably there is still 5 ltrs of fuel left in the tank and sufficient to make a run to the nearest bunk. I do the refulling normally when the indication comes on as this helps me calculate the FE.
+1. This is the perfect way to check your FE and also to ensure your car doesnt run dry

For any mid-size sedans like Fiesta, Verna the tank capacity is approx 45-50 Litres. So when low fuel warning lamp comes up you still have a minimum of 5-7 litres and its the right time to re-tank up

I follow the same practice with my Cruze

I tank up and wait for the first low fuel warning lamp comes up and normall fill up the tank within 10kms from the low fuel warning lamp sighting

Its so accurate that at each such tankful, i top up 49L-51L of fuel. Cruze has a 60L tank capacity so their is plenty in reserve

And, 90% of the time, I time my refuelling so I do it from my favorite bunk

Btw, I too have always tanked up and never understood the concept of filling gas worth Rs.500 or Rs.1000. IMO, if you drive the car alone, it always make sense in every way to always TANK UP
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Old 25th January 2013, 16:45   #22
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Originally Posted by aroop View Post
There could be multiple reasons for this.

- If someone uses the vehicle occasionally, he may consider the Rs 500 to the cost of that particular visit / day. He may not be comfortable shelling out 2500 at one go.
Exactly my reason. I use my own car very occasionally. 6/7 days it is my dad's car that i use. For a casual trip once in a week, i dont feel that i should fill 2500 worth of fuel.
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Old 25th January 2013, 16:58   #23
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

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Originally Posted by searchingheaven View Post
I am a very conservative kind of person & i usually let my fuel tank run empty before filling up. I keep a 2 litre gasoline jar filled with me for emergencies...
How does being conservative translate into running the fuel tank to empty? If anything the more you keep it to the full, the less you will loose to evaporation making you conserve even more!

Not sure about the fuel becoming 'stale', but if your daily driving is reasonable, then tanking up every 300 to 350 km (half tanks) every 10 or 15 days should keep it 'fresh' enough.

Owning a CNG car means that my petrol fuel tanks gets replenished every 40 to 50 days and my top up is only about 7 to 8 litres.
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Old 25th January 2013, 17:00   #24
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

With modern diesel engine I have learned it hard way. My Innova was in reserve (reserve light had just come on), on my way I stopped at the petrol pump but the queue was long and decided to fill it up on the way back. On my way back on a flyover the engine became very harsh and suddenly died.

I took the auto and asked the driver to put 2 liters (using a bottle) go to the petrol pump and fill up. The driver had a very hard time restarting the car with the fuel. He had to manually pump the fuel pump to get diesel to the engine. After filling up, the fuel filter light came on indicating water in the fuel lines. I had to change the fuel filter (unscheduled), get the error code wiped from the ECU etc etc.

I was told by the service adviser that its not a good idea to keep fuel at low levels specially in modern cars. There are all chances of water residue, dirt and air to enter the fuel lines. This in turn trigger host of sensors causing ECU to activate several warnings which can mostly be reset at a service centers.

Since that day I always fill up at quarter mark no matter what and it doesn't effect your expenditure on fuel anyways.
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Old 25th January 2013, 17:10   #25
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Quote:
Originally Posted by LithiumSunset View Post
How does being conservative translate into running the fuel tank to empty? If anything the more you keep it to the full, the less you will loose to evaporation making you conserve even more!

Not sure about the fuel becoming 'stale', but if your daily driving is reasonable, then tanking up every 300 to 350 km (half tanks) every 10 or 15 days should keep it 'fresh' enough.

Owning a CNG car means that my petrol fuel tanks gets replenished every 40 to 50 days and my top up is only about 7 to 8 litres.
You might have got might my answer in the post just before this one. I drive it 20 kms a week. Not more.
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Old 25th January 2013, 17:10   #26
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

IMHO, set up a schedule to tank up, instead of arbitrarily filling fuel at random bunks, with unsuspecting cheating.

Again, this is primarily applicable for people who drive to work daily.
For people who drive for household chores or hangout, it makes sense to fill atleast half the tank and not let it go dry.

I travel from BTM to Whitefield daily + Weekend grocery + hangouts.
So, I tank up my Beat at the Shell Siddapura, Varthur Road, B'lore on a Friday morning every 2 weeks. This keeps my headache away for 2 weeks
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Old 25th January 2013, 18:08   #27
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

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Originally Posted by mobike008 View Post
Venu, isnt that a bit of contradictory statement? I mean when you say tankful-to-tankful and not waiting till Low Fuel Warning Lamp comes up?
Nope, you did not get it right. I was commenting on @ghodlur's statement that instead of depending on the low fuel light to calculate FE, the acid test is by following the tankful-to-tankful method.

As Fiesta owners know, the DTE is a wee bit erratic. But the low fuel light comes on only when the reading is 80 kms on the DTE. So if I've driven with a heavy foot today, the DTE may show 80 kms and the low fuel warning light would start glowing. But tomorrow morning, if I drive for few kms without AC on a light foot, and then restart the car, the DTE may show a reading above 80 kms, and the light would no longer glow!

Hence calculating FE based on low fuel light- to low fuel light cycle will not be accurate. On the other hand, deciding to tank up based on when the light glows may be fine, but I prefer filling up when the tank is half-empty.
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Old 25th January 2013, 19:04   #28
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

Quote:
Originally Posted by mobike008 View Post
Venu, isnt that a bit of contradictory statement? I mean when you say tankful-to-tankful and not waiting till Low Fuel Warning Lamp comes up?
Quote:
Originally Posted by vnabhi View Post
Nope, you did not get it right. I was commenting on @ghodlur's statement that instead of depending on the low fuel light to calculate FE, the acid test is by following the tankful-to-tankful method.

Hence calculating FE based on low fuel light- to low fuel light cycle will not be accurate. On the other hand, deciding to tank up based on when the light glows may be fine, but I prefer filling up when the tank is half-empty.
With the Tankful-to-Tankful method, it does not matter when you refuel, (empty, nearly-empty,half-full, nearly-full) as long as you calculate the FE with distance travelled/fuel filled (km/l). It's always the same proportionate ratio
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Old 25th January 2013, 20:45   #29
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

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Originally Posted by aroop View Post
There could be multiple reasons for this.
...
But I have to agree that if a vehicle is used regularly, then doing a tankful makes sense. I believe majority of the self owned vehicles being used regularly do a tankful.
True. I agree with those reasons, but I think you misread my point. I was actually referring to private car owners like all of us here who use the same vehicle everyday and still keep filling small amounts for 500-1000 bucks once in 3-4 days; wasn't referring to occasional users like @searchingheaven or other examples like cab drivers not having money to get a 1 shot fill, etc. Sorry if my post conveyed otherwise.

I know a lot of people who do this 500 bucks-a-time visits, and come up with stupid reasons for avoiding tanking up full, especially non-petrolheads who go by myth and hearsay rather than logic. One particularly bizarre reason I have heard is that a full tank of fuel will cause it to leak out of the tank when the vehicle is parked , so filling smaller amounts is better.

Last edited by KarthikK : 25th January 2013 at 20:48.
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Old 25th January 2013, 22:33   #30
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Default Re: Letting your Car's fuel tank run empty? Drop the habit!

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Originally Posted by KarthikK View Post
T
I know a lot of people who do this 500 bucks-a-time visits, and come up with stupid reasons for avoiding tanking up full, especially non-petrolheads who go by myth and hearsay rather than logic. One particularly bizarre reason I have heard is that a full tank of fuel will cause it to leak out of the tank when the vehicle is parked , so filling smaller amounts is better.
I have a colleague in my prior organization who religiously fills up only Rs 500 every time. When I asked him, he said he was saving on interest on money not spent!
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