rxbruner

In reading about the fuel to use, I've become confused. Excuse the ignorance from a "non car guy".

The car says to use low sulfur diesel. On some diesel pumps there is a sticker that labels it as low sulfur diesel "suitable for all cars....". On that same pump is says the diesel may be between 5%-20% biodiesel. They are different stickers on the same pump.

On other pumps it just has the sticker about 5-20% biodiesel but does not say anything about low sulfur anywhere.

Are they the same thing? Is there any chance of me using the wrong diesel? I'm in the suburbs so most of the gas stations just have one or two diesel pumps.

Tom B.

Where are you located? My response is limited to the US, and is to the best of my knowledge.
All #2 road diesel is now ULSD, ultra low sulfur diesel. Blends are ULSD mixed with biodiesel.
Unless things have changed, your owners manual will recommend no more than 5% biodiesel. Opinions differ widely about how much can/should be run.
If you can, buy your fuel at a location that is used frequently by other drivers so that there is turnover of the tanks, i.e., the fuel is always fresh.

IMO, the biggest concerns about fueling our TDIs are contamination (water), turnover and misfuel (gas instead of diesel). Enjoy your TDI!

rxbruner

I'm in the Twin Cities, Minnesota

uberwgn

Tom B., good summary!

Some states mandate a higher %% of biodiesel compared to what's shown in the Owner's Manual. Does VAG still say 5% biodiesel is the limit?

rxbruner

I just worry about the sticker saying 5-20% biodiesel.

What is the issue with water contamination?

delmd92

Minnesota mandated 20% biodiesel a year ago but may allow exceptions if there is a shortage. Biodiesel attracts water which can cause a variety of problems with the fuel system. Some hoses and rubber parts are not biodiesel compatible and will deteriorate when exposed, but not sure what the magic percentage is. I would hope that the rubber exposed to fuel in a modern Audi would be resistant but I am not sure. Probably an internet search could help answer. As mentioned, go somewhere that turns over diesel quickly. I tend to use QuikTrip and really have no issues. But then again, I do 20-30k a year so it doesn’t sit in my tank too long.
Never tried to fuel gas, but I have been to a couple of stations where the nozzle was replace by the fuel pump service with a gas nozzle and it won’t unlock the safety to insert the nozzle. Maddening the first time it happens, then after you figure out what is happening, different pump or better yet, different station where hopefully the maintenance crew knows the difference.

Tom B.

I believe VAG is required to honor the warranty when a state mandates a biodiesel percentage greater than that recommended in the manual -- as mentioned before certain states do that.

The biggest problem with water or mis-fueling is damage to the HPFP (high pressure fuel pump). Do some searching because it is serious if it occurs. When damaged the HPFP can force small particles of metal throughout the fuel system, often requiring the entire system to be replaced -- tank, lines, injectors, ... A very, very expensive job.

Be cautious about relying on the color of the filler nozzle as representing diesel. Around here diesel nozzles are usually green, but not always the case (BP, for example, uses green for their gas pumps, go figure). Fortunately most modern VAG CR diesels have a restrictor device at the filler that "discourages" mis-fueling, but it can still happen. Warn anyone you lend your car to (family members, etc) of the importance of making sure it is fueled properly.