Switch between biodiesel and diesel?

Fahrfuwerfuelen

Veteran Member
Joined
Dec 7, 2004
Location
Puget Sound
TDI
Jetta, 2005 (A4), Platinum Gray
mike;

How about giving us the year and model of your car. That might help in making a recommendation.

Another option is to run a mix (%) of bio and D2.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
General consensus is that if you are going to use Bio, stick with having SOME percentage in the tank. What that % is varies but most (but not all) folks agree that if you run some, always run some.
 

UFO

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Jul 31, 2007
Location
A mile high
TDI
2001 Beetle
I've been running straight D2 the last part of winter after running B50 earlier. No issues, leaks or otherwise.
 

Fahrfuwerfuelen

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Joined
Dec 7, 2004
Location
Puget Sound
TDI
Jetta, 2005 (A4), Platinum Gray
Mike:

You can probably go with B100 on a '99 TDI. However, Whitedog's advice is good as the viscosity of bio can vary and IMHO, this has been the concern for bio-related problems.
 

HotRod

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Joined
Apr 10, 2005
Location
Santa Monica, CA
TDI
2003 Jetta
I logged 55,000 miles on B99 then got some bad fuel and ran D2 for several months. My injection pump seals began to leak. $300 and several hours later all was good.

If you run a tank of D2 every so often, then it won't matter. However, running ULSD for a month or two and then biodiesel for a month or two will swell and contract the injection pump seals leading to fuel leaks.
 

mrchaotica

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Oct 4, 2007
Location
Atlanta, GA
TDI
1998 New Beetle
HotRod said:
If you run a tank of D2 every so often, then it won't matter. However, running ULSD for a month or two and then biodiesel for a month or two will swell and contract the injection pump seals leading to fuel leaks.
Is there any way to solve this problem permanently so that it is okay to switch between (say, by upgrading to some sort of biodiesel-compatible pump seal)?
 

HotRod

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Joined
Apr 10, 2005
Location
Santa Monica, CA
TDI
2003 Jetta
I don't think that there is a seal that will prevent leaks. ULSD and biodiesel have have different properties that result in swelling and shrinking.

About three years ago, I met several VW powertrain engineers who were visiting SoCal from Germany and they said that TDIs run great on B99, but alternating between fuels would lead to problems with pump seals.
 

KDG

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May 10, 2006
Location
Santa Cruz, CA
TDI
2003 Jetta TDI running on HPR Diesel
Using an additive such as Stanadyne or PowerSource when fueling with D2 brings the aromatics level back up to levels similar to BD, and this helps prevent seal shrinkage.
 

mrchaotica

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Joined
Oct 4, 2007
Location
Atlanta, GA
TDI
1998 New Beetle
KDG said:
Using an additive such as Stanadyne or PowerSource when fueling with D2 brings the aromatics level back up to levels similar to BD, and this helps prevent seal shrinkage.
Oh, good to know! I think that's the extra reason that'll finally get me to start using PowerService (at least when I'm not using bio).
 

kcfoxie

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Feb 6, 2007
Location
Raleigh, NC
TDI
'12 6-spd JSW
Remember that the whole leaking seal business is an older car problem. I've had no leaking switch back and forth with my 82k 2006; but it never saw much LSD; just ULSD (I ran it on B100 for all of 2007 to let ULSD saturate the market before I let the car get used to any non-bio fuel).
 

Thorne

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Jul 22, 2006
Location
SF Bay Area
Was running only B100, but work mileage quadrupled, so I'm currently running mostly ULSD and adding two pints of B100 to every tank. Occasionally I'll fill up with B100.

Per most of the information I've found or read on this most excellent Forum, that min 2% mix should keep the seals in good shape.
 

KDG

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May 10, 2006
Location
Santa Cruz, CA
TDI
2003 Jetta TDI running on HPR Diesel
Thorne said:
Was running only B100, but work mileage quadrupled, so I'm currently running mostly ULSD and adding two pints of B100 to every tank. Occasionally I'll fill up with B100.

Per most of the information I've found or read on this most excellent Forum, that min 2% mix should keep the seals in good shape.
If 2% is all that's needed, then my IP seals failed (at 98k) for some other reason b/c I never went below B50. Some claim the biodiesel itself is responsible for destroying the seals. The debate rages on, but I'm still burning B99 most of the time, and now I use an additive if I add any D2 at all.
 

kcfoxie

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Feb 6, 2007
Location
Raleigh, NC
TDI
'12 6-spd JSW
Its funny you say that because I ran B100 for so long because I didn't want to shock my seals with LSD (still available at the time I got the car) and only expose them to ULSD... because it's the removal of sulphur that supposedly shrinks the IP seals.

I figured a 0-sulphur fuel would do the trick.
 

2000m2

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Apr 20, 2005
Location
USA
TDI
05 Passat
I have not had any trouble switching back and forth, but I guess I always have a little biodiesel in there. The percentage varies greatly though.
 

KDG

Veteran Member
Joined
May 10, 2006
Location
Santa Cruz, CA
TDI
2003 Jetta TDI running on HPR Diesel
kcfoxie said:
Its funny you say that because I ran B100 for so long because I didn't want to shock my seals with LSD (still available at the time I got the car) and only expose them to ULSD... because it's the removal of sulphur that supposedly shrinks the IP seals.

I figured a 0-sulphur fuel would do the trick.
Ah, maybe that's why mine failed. The car was fueled by its first owner with Low Sulphur Diesel for it's first 3 years. (I still can't bring myself to using LSD as an acronym for something that fuels a car!)
 
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