Diesel additives needed or ?

[Markergi]

Hills make a big difference, I'm also a bit anal about watching the average mpg showing on the computer in the car, I have to reset it after a few miles if I've been booting it, as I can't bare to see it less than 25 mpg and I tell myself that's not typical anyway, so a reset is required!! I do a fair few miles between West Wales and London and typically get around 28 mpg until after Newport and then 31-33 between Newport and London. I've come to the conclusion that you use a lot more fuel going up hills than you save coming down the other side!

 

[BruceK]

I get 45-50 MPG on my trips over to the boat, just saying:encouragement:

Yes but you are used to a max speed of 6 knts, just saying

 

[BruceK]

Hills make a big difference, I'm also a bit anal about watching the average mpg showing on the computer in the car, I have to reset it after a few miles if I've been booting it, as I can't bare to see it less than 25 mpg and I tell myself that's not typical anyway, so a reset is required!! I do a fair few miles between West Wales and London and typically get around 28 mpg until after Newport and then 31-33 between Newport and London. I've come to the conclusion that you use a lot more fuel going up hills than you save coming down the other side!

You might have a point. London to Conwy is all uphill So you also reboot the trip logs, and here I thought I was the only sad git trying to delude myself. 28mpg to Chester tahnks to Rhuallt hill, 33 once on the M56 and 31 on M6 South. I'm a blimmin anorack

 

[superheat6k]

Personally dont care if SM fuels are same standard, sub standard or even better standard. I get tank averages of 26mpg on Tesco and 31mpg on BP standard in the Landy. Tells me all I need to know.... any savings on Tesco are more than lost on range. Why this should be, not really concerned but somewhat amused at myself at how I religeously keep an eye on mpg in the car but use the boat with gay abandon.

Not sure what the tolerances are, but fuel pumps do have an operating tolerance. An accurate fuel pump could possibly be adjusted to deliver accurately at the bottom of the tolerance band, and this owl deb perfectly legal.

Not sure Tesco would get away with 15% less by volume, but that is some deviation.

Fuel also expands and contracts with temperature. Buying fuel on a cool morning makes sense rather than on a warm afternoon.

Oh yes Hamble has a large BP fuel distribution depot, and we see plenty of Tesco fuel tankers en route to and from, as well as myriad others, but never Texaco, Shell nor Esso.

 

[Latestarter1]

Not sure what the tolerances are, but fuel pumps do have an operating tolerance. An accurate fuel pump could possibly be adjusted to deliver accurately at the bottom of the tolerance band, and this owl deb perfectly legal.

Not sure Tesco would get away with 15% less by volume, but that is some deviation.

Fuel also expands and contracts with temperature. Buying fuel on a cool morning makes sense rather than on a warm afternoon.

Oh yes Hamble has a large BP fuel distribution depot, and we see plenty of Tesco fuel tankers en route to and from, as well as myriad others, but never Texaco, Shell nor Esso.

BS EN590 defines Cetane in a band between kg/m³820/845 @ 15 Degrees C which is a pretty tight. This difference in a test cell would make a difference of 2 to 3% absolute maximum.

As to fuel pumps, trading standards say a pump dispensing within legal limits limits is very accurate. Tolerance band is 0.5% less or 1% more than what is requested.

15% difference is simply daft non data based 'dock talk' and it is also a fact that supermarkets draw very significant quantities of their fuel supplies from BP and Shell.

Some modern fuel systems sense fuel temperature and use algorithm to modify fueling.

 

[BruceK]

I'm getting blinded by science. One of you fellows just going to have to volunteer to come on a drive with me and tell me where I'm going wrong then because I'm not making it up.

 

[rafiki_]

Diesel performance and fuel consumption is significantly affected by ambient temps. My Bimmers suffer a 10% ish reduction in fuel economy over the winter months compared with summer. Much of this I attribute to thicker oil at start up, until fully warmed-up, overfuelling, plus more draw on the heating and electrics, seats, lights etc.

 

[TK Blue MAX]

Maybe the temp, but I have often thought that do they add a anti freeze to the diesel in the winter as you don't seem to get wagons freezing there fuel lines any more ,years ago hard shoulders and motorway service stations were full of trucks with waxed fuel in the lines ,but if a additive is used maybe it doesn't burn resulting in poorer fuel economy in the winter???

just a thought

 

[Latestarter1]

Maybe the temp, but I have often thought that do they add a anti freeze to the diesel in the winter as you don't seem to get wagons freezing there fuel lines any more ,years ago hard shoulders and motorway service stations were full of trucks with waxed fuel in the lines ,but if a additive is used maybe it doesn't burn resulting in poorer fuel economy in the winter???

just a thought

Diesel does change in the winter, used to be at the beginning of November in UK. Additive package changes slightly to avoid 'waxing' of diesel fuel which clogs fuel filters. Point at which waxing occurs is known as the 'cloud point'. There is a specific test for the Cold Filter Plugging Point (CFPP).

Change to winter fuel does result in slightly worse fuel consumption, nowhere near as marked as it used to be due to improved additives, whilst no need for in in marine market at our ambient temperatures we will still get it.

Once started modern diesel engines particularly those employing unit injectors have high fuel return rates system soon warms through keeping fuel well above the cloud point despite the wind chill caused by vehicle speed. Quite the opposite to boats where we want to keep fuel return cool.