Fueling question

It took about 3-4 months to get the letter.

I'm still going to fill mine up at the same BP station I used for my Jetta. They only have B11, never had an issue with contaminated fuel, keeping my fingers crossed.

FormerOwner said:

Ok TDI'ers... put your biases aside and answer this question...

Why can't we fuel our Passats with a concentration of, say... >10% Biodiesel?

What are the effects of running biofuels >10% in this engine?

I'm seeing a growing number of fuel stations with their pumps being labeled as including concentrations of B5-B20 into their D2 tanks.

Thanks in advance for your input. Remember, please keep your biases aside; I'm trying to understand why biofuels aren't too welcome in our setup.

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Post injection for regeneration. Dilutes the oil. Requires decreased miles between oil changes.

Thanks passattdi!
Thanks to all !

So what I'm deducting from this thread is that if one were to do a dpf delete (off road use only) we could run B100 without a problem?

Oregon requires a min of B5, my oil level grew from full to just above the little ridge on the full side over 10k. After a delete with tune I wouldn't see why one couldn't use B100- im a huge fan at how friggin clean the thing runs... but I also like freedom on bio fuels and not funding the middle east with our driving requirements. My old Dodge 4x4 diesel burns everything from SVO to non synthetic waste motor oil perfectly smoke free and gets 22mpg I kinda like that

oswegoPD said:

It took about 3-4 months to get the letter.

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We bought our Passat the first week of July last year; I have yet to receive any communication on the subject of fuel from VW. (And, yes, they've got my address, because they sent me an update DVD for the RNS-510 nav unit.....an update that was older than the one I have).


Notes: The first (10K) service was performed last week. The oil on the dipstick had gone from the upper groove, slightly down to just below the top of the hash marks, probably 1/8" in 10K miles. So whatever biodiesel mix I'm getting in this car, it doesn't seem to be adding to the oil volume. I've filled up at different stations, a consequence of a lot of trips. When local, I try to fill up at the same station, a Thornton's. I've dosed the fuel with Opti-Lube XPD since the beginning, except for the big trip to Florida we just got back from. On that one, since we were facing frigid temperatures on the return trip, I used heavy doses of Power Service white coming North.
I considered and rejected the idea of a UOA on the first oil change, from the standpoint that the factory fill of oil would probably be atypical anyway, from what I've seen online. Maybe at 20K.

mihneagabriel said:

So what I'm deducting from this thread is that if one were to do a dpf delete (off road use only) we could run B100 without a problem?

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I wouldn't do it but if you do I'd be interested in the results.

mihneagabriel said:

So what I'm deducting from this thread is that if one were to do a dpf delete (off road use only) we could run B100 without a problem?

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Well you wouldn't have to worry about the oil dilution anymore and I'm sure it would run fine untill the normal issues with b99 came about.

Softrockrenegade said:

Well you wouldn't have to worry about the oil dilution anymore and I'm sure it would run fine untill the normal issues with b99 came about.

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Which would be? Sorry just haven't done much research on biodiesel. (I live in Texas where we don't really care about bio stuff much)

Since the newer models have come out (PD's and CR) the injection pressures are much much higher and hotter and may cause issues long term. I have read and seen pics here that show injector fouling over long time frames that IIRC has been said to be unclean-able and must be replaced. The holes in modern injectors are very very small for a fine mist spray pattern. I ran my 2006 Jetta TDI on B100 for a year with no ill effects and they have similar pressures and fuel temps as the CR engined cars. Deleting the emissions equipment and retuning it though will be expensive on any late model CR car ($2k to $3k).

I am in Texas too and there are those of us who do care about the bio stuff here. Here in Austin we used to have the most fueling stations with bio available in the country. TxLED changed that though. I used to make my own when I had the 2006 Jetta.

kydsid said:

Other than checking the oil there isn't any mechanical reason up to 20% bio in a CR diesel afaik. Above that the injector pressures and temperatures a CR diesel sees may lead to breakdown of the bio and varnishing of the injectors. Where is that limit? I don't really know other than to say most other CR bio limits are around 20%. I'd guess that even 20% is assuming some margin of error.

Is there something more specific to a Passat? Not that I know of. I don't worry about any bio concentration myself I just fuel up. I personally think vw's bio limit is too low. It is the lowest out there for any CR diesel I know of.

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What this guy said, plus there's less energy content per volume in biofuels; that's the main reason I wouldn't high percentages if I didn't have to. To give you a comparison, I can get 815mpt on 5% bio, whereas I only get about 640 on 20% bio.

Something wrong there. There is only about a 10% difference in energy content between diesel and B100. The difference between B5 and B20 should not account for such a large drop in miles.

http://www.fueleconomy.gov/feg/biodiesel.shtml

Only a 2% difference between D2 and B20, so less than that for B5 to B20.

FormerOwner said:

Ok TDI'ers... put your biases aside and answer this question...

Why can't we fuel our Passats with a concentration of, say... >10% Biodiesel?

What are the effects of running biofuels >10% in this engine?

I'm seeing a growing number of fuel stations with their pumps being labeled as including concentrations of B5-B20 into their D2 tanks.

Thanks in advance for your input. Remember, please keep your biases aside; I'm trying to understand why biofuels aren't too welcome in our setup.

Click to expand...

passsattdi said:

Post injection for regeneration. Dilutes the oil. Requires decreased miles between oil changes.

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Not necessarily. See my response below.

mihneagabriel said:

So what I'm deducting from this thread is that if one were to do a dpf delete (off road use only) we could run B100 without a problem?

Click to expand...

Possibly if you have software to eliminate the post cycle injection. No one knows for sure yet.

oswegoPD said:

Only a matter of time for the DPF or HPFP to go out on this one

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On the NMS Passat? My personal opinion is that we won't see the same issues that were experienced on the earlier CR TDI's. For example, the MkV Jetta failures were being reported on an almost weekly basis from the date of release. The NMS passats have seen no reported failures here on TDIClub as a result of bad fuel quality. There have been a few reports of failures directly attributed to misfueling.

IndigoBlueWagon said:

They're not going to give you one, because they don't want the liability. You'll have to draw your own conclusions based on owners' data. But there are variables here, one of which is fuel quality. Here's what you do know: VW allows more than B5 in Illinois, cautioning owners to watch oil level to make sure it doesn't rise. And I've read about folks here running B20 with no issues...so far.

Maybe someone knows a VW employee who'll talk "off the record."

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Well, seeing as I am no longer employed by a Vw dealership....

I have 50k miles worth of oil analyses from my 09 Jetta and 20k miles worth of oil analyses from my Passat. I NEVER saw a rise in oil level and NEVER saw oil dilution as a result of using 10% Biodiesel. I specifically asked Blackstone to test for oil dilution as a result of using B10 and every time they said flashpoint was ideal, viscosity was very good, and there was no dilution from fuel.

I suggest for anyone who wants to go above the factory approved B5 Biodiesel to get their own oil analysis done and come to your own conclusions....

I also believe this may be attributed to my monthly long distance trips. If you do a lot of city driving or short trips, you may experience more frequent re generations leading to possibly more oil dilution.

^^^Sorry to hear the news. Hope you're moving on to something even better!

Well, I have moved out to nevada with my brother in law and sister. I am considering trying to get in with a Vw dealer out here. But we will see what happens.