lja36

more good stuff here

http://pics.tdiclub.com/data/529/Die..._-_Chevron.pdf

lja36

And I can personally testify that the Q5 TDI runs very differently on European diesel compared to US diesel (WA state at least), even the supposedly expensive branded stuff. Unless it is contaminated, I don't really perceive or expect any difference; the engine doesn't really like it and sounds like a old cummins truck in comparison to when I was driving all over Europe with it.

If you haven't run your Q5 TDI with diesel that is on par with European diesel you have not fully experienced the engine.

Of course my solution is to run cetane enhancers which work, but I'll try harder not to become too pushy about it...

gojones

Should we run cetane enhancers and if so, then what brand. Should we use them occasionally, frequently, or etc. What is the general thinking on this. Other forums are all over the board on this subject. Does it void the warranty?

Don Keener

Ive got exactly the same question... to add(itive) or not to add(itive)....
Just did my first full tank mpg calculation and got 29.4 in and around town.

I wonder if the fuel that comes in the car when you pick it up from the dealer came from Europe or from the US port or dealer? The car did seem quieter on that first 3/4 tank of fuel.

Q5 TDI

GasBuddy is a great app worth getting since you CAN filter on diesel stations - however - what they indicate as top tier stations can include biodiesel stations - so beware! I've contacted them several times about creating a filter to ignore biodiesel stations without any response.

Similarly - I asked what makes a station "top tier" other than the station paying for the label - again no response from GasBuddy.

SJGQ5

i don't think GasBuddy will be able to tell you about Top Tier..

However..

Top Tier Gasoline

Explains it…Also I don't think Top Tier applies to Diesel..just gas..

audi40

There has to be some fuel in the cars when they come from Europe since they have to be driven off the boat, but I doubt they come with a full tank from Europe.

idale

Correct, "Top Tier" is a petrol certification that brands can apply for. At this time there's nothing similar for diesel. So a "Top Tier" station just means the petrol they have is certified under the "Top Tier" requirements, but won't say anything about their diesel.

As for using additives, ideally you wouldn't but depending on what the fuel quality is like in any given area you may need to in order to run smoothly. I don't have any issues around here (usually -- this current tank is running rougher for some reason and performance is definitely down for the first time in my ownership), but in other areas cetane can be a lot lower (48+ minimum in TxLED counties, 40+ minimum in general for the US, I think Europe's something like 50+ minimum).

Additives shouldn't cause warranty claims to be denied, but the more you use the more potential you have for them to balk if you have fuel-related trouble (quality additives shouldn't be an issue, I'd imagine, just make sure it's not random stuff as European engines tend to be picky about what goes into them). I'd check with my local dealer for recommendations on whether they think it'd be good to use anything in your region, as well as what their policies are on additives (if they're for them, then they should go to bat for you on warranty coverage of fuel-related problems, if they're against them then you may have a harder time).

lja36

I have an older VW TDI that over the years became rougher running, smokier and harder to start in the cold. The dealer told me to use cetane enhancers and even gave me a big bottle of it. They said that US diesel sucked. All my problems went away, I was an instant convert.

A couple of years later when I got a Q5 TDI and drove it in Europe, the difference between European diesel and US diesel was quite noticeable. I started using cetane enhancers right away (Power Service). There were one or two people who claimed that it would void warranty etc... I looked in the owner's manual, absolutely no mention of it aside from using >5% biodiesel.

Just for laughs, I asked my dealer service advisors and they said, absolutely, the stuff is fine, they even use it for all their commercial and loaner diesels. If you are afraid, check with your dealer first and then check with AoA if you really want to be sure.

But you have to ask yourself: how can something that helps the fuel burn better be harmful? It is really the other way round. Slow burning diesel will cause more soot generation and stress the DPF and the regeneration mechanism a lot more.

DimaA6_ABC_Kiev

51. Sometimes premium diesel fuel has cetane number 54 or 55.