Last post on Nov 17, 2013 at 8:38 AM
You are in the Volkswagen Jetta
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Volkswagen Jetta, Biodiesel, Diesel, Sedan
#2314 of 4777 Low Sulphur Diesel vs. Ultra Low Sulphur Diesel fuel economy
Aug 26, 2008 (3:32 pm)
Does anyone else who owns a pre-2007 VW diesel have any comparison regarding real world fuel economy using ULSD (15ppm)vs. "regular" low sulphur (500ppm) diesel? It may just be me but I seem to notice a definite drop in fuel economy when I use ULSD in my 2005 Jetta. At first I thought it was just the car, but then I happened to fill up on a tank of 500ppm at a local station and noticed an almost 25% increase in fuel economy (39-42mpg on ULSD vs. 48-51 on 500ppm diesel).
Does anyone else have an experience like this or am I just crazy? I can't attribute it to my driving habits since I drive the same speed, route and distances to and from work every day. I've also noticed the mileage boost seems to "linger" on my next tank if I happen to fill up next time on ULSD. However, if I fill up twice on ULSD I drop back to the low 40's.
I first noticed my mileage drop about 6 months ago when most of my local stations switched from 500ppm to 15ppm diesel. Last year when I took a road trip to Tennessee I averaged 52mpg, but on the same trip this year averaged only 41mpg. However, I never started to put two-and-two together until recently.
#2315 of 4777 Re: Low Sulphur Diesel vs. Ultra Low Sulphur Diesel fuel economy [inlarry]
Aug 26, 2008 (5:28 pm)
Are you buying from the same station? While sulphur content shouldn't effect performance, the fuel itself could. It could have a lower cetane which is what I typically noticed would effect mpg the most. I tried to always run BP Diesel Supreme which was a 15ppm high-cetane fuel. I got slightly better mpg along with quieter operation and zero smoke, even on cold startup. If I filled on normal diesel I could immediately notice a difference. So I would not give up on the ULSD but perhaps shop around for a better fuel. Many local stations will buy fuel from the same distributor so it could take some shopping around. And brand-name doesn't always mean that's the fuel they're using, particularly diesel. There were only two stations within 30 miles of me that actually carried BP Diesel Supreme. The other BP stations bought from a no-name regional carrier.
#2316 of 4777 Re: Low Sulphur Diesel vs. Ultra Low Sulphur Diesel fuel economy [sebring95]
Aug 26, 2008 (5:47 pm)
I agree with sebring95 - It is the CETANE which has the biggest affect on MPG. The VW TDI engines are really rated for European fuel. The diesel in NorthAmerica does not quite meet the cetane which the TDI is specd. for.
That is why I always add ~6oz PowerService diesel fuel additive with each fillup. Not only does the PowerService increase the cetane to where the engine wants it... I also get added lubricant for the expensive injection pumps. (And some injector-cleaning detergents too)
I log every drop of fuel that goes into my TDI and keep a spreadsheet of MPG. There is no question that when my wife fills the car (and does not add PowerService) that I lose about 3-5 MPG.
Anyone who drives a TDI in NorthAmerica should consider fuel additive as part of owning a diesel engine. PowerService is available at any WallyMart. (Use GREY bottle in summer and WHITE bottle in winter)
#2317 of 4777 Re: Low Sulphur Diesel vs. Ultra Low Sulphur Diesel fuel economy [inlarry]
Aug 26, 2008 (5:52 pm)
This bring me to the question of whether the new low sulfure diesel have enough lubrication or not? My guess, this new Diesel fuel is lucking the lubricatoin that allow the high compression diesel engine to operate with extrem efficiency. As far as the new Diesel engines are concerned the design did take in account the new fuel molecular structure. but the fact that the new Diesel engine fuel efficiency is falling short of the previous engine results is because of the new Catalytic converter is too restitrictive, and the fact that the chemical reaction in this enclosure require the computer to release extra diesel in the catalytic converter to get rid of NOx. still 41 MPG for a car the size of Jetta is a good number.
Aug 26, 2008 (7:29 pm)
I have an 06 TDI with all options including DSG. I chose the DGS over the manual because the DSG gave better acceleration, especially in S mode. The BIG drwaback is the maintenance cost - over 500.00 at 80K miles. The trans needs an oil change but the trans is sealed!
I live in the Tampa area andam considering setting up a biodiesel conversion. Would anyone from the Tampa area like to participate? The basic set up would be 1200.00 but a better (more gallons less effort) can be had for 4000.00 split 5-8 ways would make the capital cost less with more efficient production of 200 gals per week.
#2319 of 4777 Re: Biodiesel [ed_grant]
Aug 27, 2008 (4:33 am)
I do not think the Biodiesel is good idea. They are a lot of people that had the engine rebuilt or the injectors changed because they get glazed from overheating. Biodiesel is fuel that has a high percentage of lubricity, and thatís translated to high energy and heat. So, the Diesel engine need to be converted prior to using the Biodiesel or else youíll be looking at anywhere from $600 to change the injectors to $4000 for new engine. I do not think itís worth the saving you expect to make from using Biodiesel. But there is a good way of taking advantage of the Biodiesel; by mixing regular diesel with 20% biodiesel, it will give you more lubrication that is lacking from the new low sulfur diesel.
#2320 of 4777 Re: Biodiesel [malmouza]
Aug 27, 2008 (5:19 am)
There are a lot of people using 100% biodiesel with NO problems at all. I provided a list of the companies that only use biodiesel in their fleet. Most have VW TDI cars that run on B100. There is a problem with biodiesel and older diesels in that it is a solvent that will clean out the fuel lines. You would need to change your fuel filter often until all that crap is cleaned out. I have not read one case of a vehicle running on just biodiesel being damaged. It will gel in cold weather. It is ideal fuel for people in warm climates like CA. It is also the only practical renewable fuel. I do not advocate making biodiesel from food stocks. Until algae biodiesel is widely available waste oil is the best source.
Willie Nelson uses B100 in his Mercedes he keeps on Maui. There is no downside running B100 where it is available. Do not confuse biodiesel with waste vegetable oil. They are NOT the same. This company has had a lot of success over the last several years renting VW Beetles that only use biodiesel.
Aug 27, 2008 (5:40 am)
A lot of people get Biodiesel and Waste Vegetable Oil Confused. Biodiesel is made from WVO(waste vegetable oil)
Biodiesel is made by removing the Glycerine from the WVO,by various processes,including the use of Lye and Methanol.This causes the glycerine to separate from the oil.
WVO is filtered using a 10 micron or better filter.If there is a chance of water contamination,then it is also dewatered.
A WVO conversion involves the use of a Tank Heater,Heated Filter,Line Heater,Switchover Valve,etc. 2 tanks are used,diesel and vegoil.Car is started and warmed up on diesel,then switched to vegoil. It is switched over to diesel just before(3 minutes) arriving at your destination.
#2322 of 4777 Re: Biodiesel [gagrice]
Aug 27, 2008 (6:06 am)
I do not think you're getting the full story. Most people that have success with the biodiesel from WVO, had their engine converted with separate tank for the Biodiesel. They start the car on regular diesel and switch to biodiesel after the engine is warm. Go to TDI forum and you will see how many problems people are having with the use of biodiesel. Personally I will not venture in using Biodiesel in my car unless my car is junk car and I do not care what going to happen to the engine.
Concerning the Biodiesel everybody knows where the biodiesel comes from. You can just google it I will get tremendous amount of information.
#2323 of 4777 Re: Biodiesel [malmouza]
Aug 27, 2008 (6:59 am)
You are misinformed. Biodiesel is a product that can be made from waste vegetable oil and many other things including soy beans, rapeseed, and algae. I agree that running WVO has its problems. Biodiesel is a direct replacement for diesel. You do not use the two tank system with biodiesel. You do NOT get biodiesel from your local chinese restaurant. You get old cooking oil. It is NOT the same as biodiesel.