Diesel The Fuel

[rory]

Hello everyone.
I'm new to VW TDI s and have the 2009 1.6 litre Jetta with DSG.
Has anyone checked out the relative consumptions of their TDI with different makes of fuel ? and would like to share their findings ( ie which brand at the pump gives you the best economy ?)
Is it a fact that VW recommend a brand over others as being prefered ( or preferable) ? If this is so, is it in fact BP?

[vampie.boy]

Hi,

I got the best results with Shell diesel both here and in Europe. I have a 2004 Passat TDI PD with 96Kw 1.9 engine. Averages consistently 550 miles on a tankfull.

[Transporter]

Go by cetane no. recommended for your engine and select the fuel that has required CN. I use BP diesel, since it has the highest CN as far as I know. How ever, if you find out that where you live your engine runs better on other brand fuel, go for it.

[benough]

I generally stick to BP and Shell if I can't get BP. I'm trying this Caltex Vortex Premium Diesel atm, see how it goes.

[Cousin]

Have been using Caltex Vortex for the last month or two. No difference in consumption compared to BP diesel (not premium) but far less black smoke out the back
I'm guessing that's gotta be good for the DPF so I'll stick with it



M

[benough]

Sorry to nitpick Cousin but if you have a DPF you don't blow ANY smoke. IF you can see smoke from whilst driving the car then I highly doubt you have one or it's kaput but I'm sure the dash would be lighting up if that was the case...

[Cousin]

That thought occured to me Benough
I've got a 2006 Multivan TDI
A kick back under heavy acceleration now gets very minor smoke
Running standard diesel I'd leave a black cloud behind on first kick back, less on the second, and bugger all on the third
Night time with a car behind and headlights I'll see some smoke changing past 3 grand, but not a lot
I'll get a shot of the exhaust off the engine, and what I presumed was the DPF
Can't say I really went looking for the cat, the big lump might be that
I'd be more than happy to find I'm wrong, one less bloody expense to worry about


M

[tonymaroney]

One thing worth pointing out is that the fuel economy is one important thing, but the "cleanliness" of the diesel or the way it burns is another...when I first starting driving my 2L TDI Golf V 2005 (103 kW, no DPF) I was using Woolworths (Caltex, standard grade? not the good stuff) diesel because it was cheap AND I got good economy from it. I tried other brands and seemed to get worse economy (and I was being relatively careful to keep the driving conditions as uniform as possible across the different brands I was testing). BUT the smoke I was getting out the back from the WW diesel was BAD (as in, I filled the street with unburnt brown particulates), and while I loved the economy boost (extra 50-90 klms I estimate, consistently from the tank) I really didn't like the smoke. Firstly I tried several brands of diesel conditioners, and some did help (Moreys Diesel Smoke Killer was the best IMO) but the smoke wasn't at a point where I felt comfortable. I talked to VW and a few independant mechanics about the particulates and while the diagnoses was that it was higher than the norm, it wasn't excessive and out of spec.
So I then started a different type of test...a smoke reduction test...I tried BP Ultimate Diesel and to be honest I noticed such a significant improvement that I haven't made it to the next test petrol! It's NOT perfect by any means, but a significant reduction was what I was after, and BP ultimate seems to be one most people recommend.
I thought about why a "good quality fuel" didn't necessarily translate into "high economy" and came up with multiple possibilities, some which are complex and difficult to prove and some which are very simple and had little to do with the fuel itself.
Complex/difficult to prove: The hydrocarbon profile of the cheaper fuel is quite good and suited to my engine, but the fuel hasn't been cleaned up as much to remove either impurities or heavier hydrocarbons that don't combust as fast/well. End result is good power/economy but unburnt soot going out the tailpipe and back around into the EGR (exhaust gas recirculation).
Simple possibilities: The dispensing pump calibration is "favourable" at the cheap station indicating I pumped less than I did, and thus translating to a calculation error. Or even that the tanks at the cheap petrol station are stored in ground that is cooler than the other station and thus a higher SG (specific gravity, or density) liquid is dispensed...ie I get more weight of petrol per litre pumped that at the other station. Or it could be just a slight "normal" SG(density) difference between the two diesels combined with another issue.

Regardless...I can visually see that the BP Ultimate fuel is better combusted in my engine and the slight decrease in economy could be nothing but a pump calibration etc issue, so I chose to go with BP Ultimate from now on. I also use the Moreys product too. It costs me slightly more, but I'm only filling up once a month so it's nothing compared to other bills.
Regards,
Tony

[The_Hawk]

Given a reported consumption of 5.7L/100km the pump would have to be under reading by 2.85L - 5.13L and with a 55L fuel tank your talking about an error of 5.2% - 9.3%, not something I think your average fuel station would allow since they want to make as much money as possible.

Also when it comes to SG of fuel the differences are marginal at best, from what I understand the changes are not 100% linear but to give you an idea I dug up some numbers for what I believe are automotive diesel SG. For a 50 °C change from 15°C, the change is 0.0414, so 1 L at 15°C becomes 1.0414 L at at 65°C.

Consider then that temperature fluctuations are likely to be far far less than 50°C especially underground and especially between local servos, so even if you factor in a 10°C differential your talking about an error of less than 1% due to SG... assuming of course that the servo computers that control these things don't have the smarts to adjust for these things (and if they don't I'm going to take a stab it's because the differences are so small it's not worth the effort).

All that aside it's all about the fuel you feel comfortable with from a perceived consumption vs performance perspective. I'm a fan of BP's Diesel (although I don't know that any of our locals have "ultimate diesel") as well as the "ultimate" unleaded I put into the VR6. They also happen to be local and friendly which goes a long way

[benough]

That thought occured to me Benough
I've got a 2006 Multivan TDI
A kick back under heavy acceleration now gets very minor smoke
Running standard diesel I'd leave a black cloud behind on first kick back, less on the second, and bugger all on the third
Night time with a car behind and headlights I'll see some smoke changing past 3 grand, but not a lot
I'll get a shot of the exhaust off the engine, and what I presumed was the DPF
Can't say I really went looking for the cat, the big lump might be that
I'd be more than happy to find I'm wrong, one less bloody expense to worry about


M

DPF's didn't become law in this country until the 1st of Jan 2008 so lucky for you, no big expensive bill when the DPF packs it in!