Author Topic: Fuel Recommendation vs Low Fuel Light  (Read 2840 times)

culzean

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #15 on: November 02, 2021, 03:21:54 PM »
the Jazz still drives (to a petrol station  :D).

Depends how far the petrol station is away  :-X
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

shufty

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #16 on: November 02, 2021, 04:16:57 PM »
...Assuming the dealer stopped filling at the first 'click' I managed 445 miles on first tank and it took 32.5l to get back to first click again. So about 62ish mpg.

On the mk2 Jazz I would normally wait until after the low level warning had appeared (and then some) before filling but in this instance I needed to there and then. May just fill on last bar in this car though.

I did travel 125 miles after the warning light came on once in a 1992 'k' Clio 1.1 before it coughed and then ran out as I glided into a layby on the A17  ;D (can of petrol at the ready ;))

guest9814

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #17 on: November 05, 2021, 08:05:35 AM »
If  35l enough to month or more waiting the low fuel light not best decision , best you can do if there no fuel shortage fill up after 2 or 3 bars disappear.
I filled up tank already several times after 2 bars go off (this is ~10l of gasoline each fill up in my case) and get better fuel economy,  before that I  seen  mpg drop after reaching 1/2 tank and below on every tank full to empty.
By the way I seen that PHEV and EV with range extender  asking to add fresh fuel after 90 days or car itself goes in hybrid mode to burn fuel before it will by old.
https://bestride.com/news/technology/plug-in-hybrids-and-range-extended-evs-need-to-keep-your-fuel-fresh-heres-how-they-do-it
But maybe I have bad 95 RON gasoline in my country and someone in Europe or United Kingdom will no see any difference….

Lord Voltermore

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #18 on: November 05, 2021, 02:39:07 PM »
If  35l enough to month or more waiting the low fuel light not best decision , best you can do if there no fuel shortage fill up after 2 or 3 bars disappear.
I filled up tank already several times after 2 bars go off (this is ~10l of gasoline each fill up in my case) and get better fuel economy,  before that I  seen  mpg drop after reaching 1/2 tank and below on every tank full to empty.
By the way I seen that PHEV and EV with range extender  asking to add fresh fuel after 90 days or car itself goes in hybrid mode to burn fuel before it will by old.
https://bestride.com/news/technology/plug-in-hybrids-and-range-extended-evs-need-to-keep-your-fuel-fresh-heres-how-they-do-it
But maybe I have bad 95 RON gasoline in my country and someone in Europe or United Kingdom will no see any difference….

Strange that you are getting better fuel economy frequently topping up to a full tank,  than when its often half full or less. Should be the other way round because the car is a few Kilogrammes  heavier.  Maybe your local petrol is boosted to 95 Ron with additives that are so volatile the improvement evaporates very quickly when the fuel gets sloshed around  in a half full tank.

Interesting about petrol going stale in Plug- in hybrids where some drivers may not need to use any petrol at all from their tank  for a year or more.     I have read that E10 goes stale  a bit more quickly than 100% petrol.

 Although The problem is less likely with  self charging hybrids there must  be some drivers who will be doing such a small annual mileage  they may still  have  the same petrol in the tank for months. ( Especially those who may   fill up in late summer, only do a  few miles a month, hibernate or go off somewhere warm for the winter, and still have 3/4 of a tank left to last them right through spring )    These may also need to ensure the  car gets run to keep the HV battery charged.   
  Trust a dog to guard your house  , but not your sandwich

Kremmen

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #19 on: November 05, 2021, 03:04:39 PM »
I'm not convinced that continually topping up a few litres at a time is making any real difference.

It's probably just fooling the fibometer into reporting higher mpg. The only true way is to calculate by brimming, or to the pump nozzle 'click', and doing the maths.



Let's be careful out there !

peteo48

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #20 on: November 05, 2021, 03:16:21 PM »
If  35l enough to month or more waiting the low fuel light not best decision , best you can do if there no fuel shortage fill up after 2 or 3 bars disappear.
I filled up tank already several times after 2 bars go off (this is ~10l of gasoline each fill up in my case) and get better fuel economy,  before that I  seen  mpg drop after reaching 1/2 tank and below on every tank full to empty.
By the way I seen that PHEV and EV with range extender  asking to add fresh fuel after 90 days or car itself goes in hybrid mode to burn fuel before it will by old.
https://bestride.com/news/technology/plug-in-hybrids-and-range-extended-evs-need-to-keep-your-fuel-fresh-heres-how-they-do-it
But maybe I have bad 95 RON gasoline in my country and someone in Europe or United Kingdom will no see any difference….

Strange that you are getting better fuel economy frequently topping up to a full tank,  than when its often half full or less. Should be the other way round because the car is a few Kilogrammes  heavier.  Maybe your local petrol is boosted to 95 Ron with additives that are so volatile the improvement evaporates very quickly when the fuel gets sloshed around  in a half full tank.

Interesting about petrol going stale in Plug- in hybrids where some drivers may not need to use any petrol at all from their tank  for a year or more.     I have read that E10 goes stale  a bit more quickly than 100% petrol.

 Although The problem is less likely with  self charging hybrids there must  be some drivers who will be doing such a small annual mileage  they may still  have  the same petrol in the tank for months. ( Especially those who may   fill up in late summer, only do a  few miles a month, hibernate or go off somewhere warm for the winter, and still have 3/4 of a tank left to last them right through spring )    These may also need to ensure the  car gets run to keep the HV battery charged.

Interesting points. On the issue around PHEVs we have a near neighbour with a BMW 3 series PHEV. He went six months without adding fuel and he only needed to add fuel after a lengthy road trip. He bought a PHEV so that he could do occasional long trips without the usual hassle around charging. Almost all his motoring is in EV mode.

I think the manual does suggest doing a 30 minute run in the Mk4 Jazz if not used often for the benefit of the hybrid battery.

Jazzik

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #21 on: November 05, 2021, 04:45:25 PM »
I'm not convinced that continually topping up a few litres at a time is making any real difference.

I am convinced!!! It really makes a difference! But logically thinking unfortunately a negative difference...
I don't know how it is with you all here, but normally I drive a few hundred meters, sometimes even a few kilometres extra to get to a petrol station. This causes burning some extra fuel. The more often one would do that the more (unnecessary) fuel one would burn.
I refuel our Jazz roughly every 650 - 800 km. (400 - 500 mi) and Roman suggests to refuel at least 3 to 4 times more often... How many extra (unnecessary) km./mi would one make over the years?

Next to that: 1 liter of petrol weighs about 750 grams. If you never empty your tank beyond, say, about 30 liters left, you are always driving with a minimum of 22 kg. petrol "ballast" around. And as we all know: extra weight means extra consumption...
« Last Edit: November 05, 2021, 11:02:04 PM by Jazzik »
If nothing goes right, go left!

guest9814

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #22 on: November 05, 2021, 07:29:21 PM »
I'm not convinced that continually topping up a few litres at a time is making any real difference.

I am convinced!!! It really makes a difference! But logically thinking unfortunately a negative difference...
I don't know how it is with you all here, but normally I drive a few hundred meters, sometimes even a few kilometres extra to get to a petrol station. This causes burning some extra fuel. The more often one would do that the more (unnecessary) fuel one would burn.
I refuel our Jazz roughly every 650 - 800 km. (400 - 500 mi) and Roman suggests to refuel at least 3 to 4 times more often... How many extra (unnecessary) km./mi would one make over the years?

Next to that: 1 liter of petrol weighs about 750 grams. If you never empty your tank beyond, say, about 30 liters left, you are always driving with a minimum of 22 kg. gasoline "ballast" around. And as we all know: extra weight means extra consumption...
I write this from my expiriense with my local gasoline and tank of 35 liters that last 45-50 days to empty, add to this story hot climate and possibility to get realy bad gasoline in first place.
If you not want to drove arround full fuel tankl go ahead and fill only 5 liters after low fuel apears, do this round year !!!
Tell to everyone afterward if you get better fuel economy then i have.

guest9814

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #23 on: November 05, 2021, 07:36:08 PM »
I'm not convinced that continually topping up a few litres at a time is making any real difference.

It's probably just fooling the fibometer into reporting higher mpg. The only true way is to calculate by brimming, or to the pump nozzle 'click', and doing the maths.
I drived 327 kilometers to get 2 bars of fuel meter go off then fill up to full tank (i let the fuel pump on gas station to stop automaticaly) - managed to fill up 10.8L.
Afterward i fill up after 335km and get 11.1L but this time i added to 3/4 of tank "95" RON gasoline with 98 RON, managed to get from this tank 930.7km and computer still judge that on remaining gasoline i can go another 150km
But that was in end of month and i heard about fuel price jump so filled up - get this time 30.7l to full tank (trip A 930.7KM)

guest9814

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #24 on: November 05, 2021, 07:53:43 PM »
If  35l enough to month or more waiting the low fuel light not best decision , best you can do if there no fuel shortage fill up after 2 or 3 bars disappear.
I filled up tank already several times after 2 bars go off (this is ~10l of gasoline each fill up in my case) and get better fuel economy,  before that I  seen  mpg drop after reaching 1/2 tank and below on every tank full to empty.
By the way I seen that PHEV and EV with range extender  asking to add fresh fuel after 90 days or car itself goes in hybrid mode to burn fuel before it will by old.
https://bestride.com/news/technology/plug-in-hybrids-and-range-extended-evs-need-to-keep-your-fuel-fresh-heres-how-they-do-it
But maybe I have bad 95 RON gasoline in my country and someone in Europe or United Kingdom will no see any difference….

Strange that you are getting better fuel economy frequently topping up to a full tank,  than when its often half full or less. Should be the other way round because the car is a few Kilogrammes  heavier.  Maybe your local petrol is boosted to 95 Ron with additives that are so volatile the improvement evaporates very quickly when the fuel gets sloshed around  in a half full tank.

Interesting about petrol going stale in Plug- in hybrids where some drivers may not need to use any petrol at all from their tank  for a year or more.     I have read that E10 goes stale  a bit more quickly than 100% petrol.

 Although The problem is less likely with  self charging hybrids there must  be some drivers who will be doing such a small annual mileage  they may still  have  the same petrol in the tank for months. ( Especially those who may   fill up in late summer, only do a  few miles a month, hibernate or go off somewhere warm for the winter, and still have 3/4 of a tank left to last them right through spring )    These may also need to ensure the  car gets run to keep the HV battery charged.
MTBE up to 15% more by 14% then by BP
aromatics up to 35% more by 15% then by BP
olefines up to 18% this crap prohibited in most countries because it causes smog. not used by BP
added according to Bazan group https://www.bazan.co.il/Media/Uploads/B024.pdf sorry i can't find english pdf version.
BP uses up to 20% of toluene (aromatics) and up to 1 % of ETBE so gasoline rectification on BP sites is much better i think
https://www.bp.com/content/dam/bp/country-sites/en_au/australia/home/products-services/data-sheets/premium-unleaded-95.pdf
there is E10 pdf https://www.bp.com/content/dam/bp/country-sites/en_au/australia/home/products-services/data-sheets/regular-unleaded-petrol-with-ethanol.pdf
But drivers that delivering fuel often do bad thing - they can on the way to gas station drain part of the gasoline and so that the number of liters is equal to received for delivery, they adding to gasoline  used engine oil, acetone or alcohol, what kind of gasoline gets to the gas station nobody knows except these swindlers, our organization responsible for fuel quality regularly carry out checks and find low quality gasoline at gas stations - after checking at least half a year, the gasoline there is normal.
In the south of Israel, on the way to Eilat, there are several gas stations in Arab cities, there such "high-quality gasoline" is constantly poured and checks, although they reveal violations, nothing changes.

guest9814

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #25 on: November 05, 2021, 08:38:05 PM »
If  35l enough to month or more waiting the low fuel light not best decision , best you can do if there no fuel shortage fill up after 2 or 3 bars disappear.
I filled up tank already several times after 2 bars go off (this is ~10l of gasoline each fill up in my case) and get better fuel economy,  before that I  seen  mpg drop after reaching 1/2 tank and below on every tank full to empty.
By the way I seen that PHEV and EV with range extender  asking to add fresh fuel after 90 days or car itself goes in hybrid mode to burn fuel before it will by old.
https://bestride.com/news/technology/plug-in-hybrids-and-range-extended-evs-need-to-keep-your-fuel-fresh-heres-how-they-do-it
But maybe I have bad 95 RON gasoline in my country and someone in Europe or United Kingdom will no see any difference….

Strange that you are getting better fuel economy frequently topping up to a full tank,  than when its often half full or less. Should be the other way round because the car is a few Kilogrammes  heavier.  Maybe your local petrol is boosted to 95 Ron with additives that are so volatile the improvement evaporates very quickly when the fuel gets sloshed around  in a half full tank.

Interesting about petrol going stale in Plug- in hybrids where some drivers may not need to use any petrol at all from their tank  for a year or more.     I have read that E10 goes stale  a bit more quickly than 100% petrol.

 Although The problem is less likely with  self charging hybrids there must  be some drivers who will be doing such a small annual mileage  they may still  have  the same petrol in the tank for months. ( Especially those who may   fill up in late summer, only do a  few miles a month, hibernate or go off somewhere warm for the winter, and still have 3/4 of a tank left to last them right through spring )    These may also need to ensure the  car gets run to keep the HV battery charged.

Interesting points. On the issue around PHEVs we have a near neighbour with a BMW 3 series PHEV. He went six months without adding fuel and he only needed to add fuel after a lengthy road trip. He bought a PHEV so that he could do occasional long trips without the usual hassle around charging. Almost all his motoring is in EV mode.

I think the manual does suggest doing a 30 minute run in the Mk4 Jazz if not used often for the benefit of the hybrid battery.
This recomendation surely to charge battery but small 12v one, i have voltmeter with 12v socket fitted and when i start car i see 14.7v on voltmeter but after driving for ~20-30 minutes without huge load on 12v battery i can see that voltage drops to 12.7v (yes our dc-dc charger not topping up 12v battery constantly).
To top up HV battery to 95% enough to run engine for 5-6 minutes  by pressing accelerator pedal when car is stationary in Parking (P).

nowster

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #26 on: November 06, 2021, 01:41:41 PM »
I think the manual does suggest doing a 30 minute run in the Mk4 Jazz if not used often for the benefit of the hybrid battery.
This recomendation surely to charge battery but small 12v one, i have voltmeter with 12v socket fitted and when i start car i see 14.7v on voltmeter but after driving for ~20-30 minutes without huge load on 12v battery i can see that voltage drops to 12.7v (yes our dc-dc charger not topping up 12v battery constantly).
To top up HV battery to 95% enough to run engine for 5-6 minutes  by pressing accelerator pedal when car is stationary in Parking (P).
No, it specifically mentions it is for the benefit of the HV battery.

Kremmen

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #27 on: November 06, 2021, 02:36:30 PM »
What I find odd is that on the 2 occasions I've used a CTEK to fully charge the 12V battery after not using the car for a couple of weeks, on next powering up the battery segments go right up to max then tail off during driving back to the normal 3 to 6 variable segments.
Let's be careful out there !

Lord Voltermore

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #28 on: November 06, 2021, 03:45:21 PM »
I'm not convinced that continually topping up a few litres at a time is making any real difference.

It's probably just fooling the fibometer into reporting higher mpg. The only true way is to calculate by brimming, or to the pump nozzle 'click', and doing the maths.
I drived 327 kilometers to get 2 bars of fuel meter go off then fill up to full tank (i let the fuel pump on gas station to stop automaticaly) - managed to fill up 10.8L.
Afterward i fill up after 335km and get 11.1L but this time i added to 3/4 of tank "95" RON gasoline with 98 RON, managed to get from this tank 930.7km and computer still judge that on remaining gasoline i can go another 150km
But that was in end of month and i heard about fuel price jump so filled up - get this time 30.7l to full tank (trip A 930.7KM)
I dont think filling to the first click auto stop on the pump is consistent enough between pumps for  precise comparisons on small quantities over a short period.    With a fast pump the filler neck on the car may fill up with fuel faster than it can  drain down into the tank. Especially when its almost full  . The pump detects this backlog of fuel in the filler pipe as a full tank and clicks off early. After a few seconds maybe half a litre or more of this trapped fuel  will have drained down into the tank.  With a slower pump there is no such backlog and you can fill up with that much more  fuel. Seems like you have used more for the same distance, but you haven't really.

The only way to do it accurately is to brim the tank until fuel is literally visible in the filler neck.  But this is not very safe, especially in a  hot climate where the petrol may expand.

Sound like your local  petrol is  using some dubious additives.  Even before it is adulterated further by criminals.

If there is a risk of a very bad batch of petrol it makes more sense to buy little and often.  If you add 10 litres of bad petrol to 30 litres of 'good' petrol you may never know.  Add 30 litres of bad to 10 litres of good and you'll know all about it. :o
  Trust a dog to guard your house  , but not your sandwich

Kremmen

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Re: Fuel Recommendation vs Low Fuel Light
« Reply #29 on: November 06, 2021, 03:56:26 PM »
I agree, which is why after the first click I let it 'fizz' down for a few seconds, before the pump cuts out through inactivity, and then drizzling in to get a second click.

I just didn't want to make it sound more complicated :)
Let's be careful out there !

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