[silvershadow]

My partner is about to purchase an EOS TDI DSG and during a discussion with the salesperson about servicing the TDI engine; mention was made of the fact that use of bio-diesel will void the engine warranty. The salesperson advised one of their customers had encountered engine problems after using bio-diesel and VW had declined warranty cover for the necessary repairs.

I have not seen any specific warnings to this effect in any of the VW websites/forums and would appreciate confirmation/ rebuttal of this prohibition. Given the increasing sale of bio-diesel blends in my part of Australia and the inability of service station staff to confirm whether their fuel is mineral diesel or a blend; I am very concerned about the possibility of unavoidable use of bio-diesel prejudicing the vehicle warranty. The pressure from vested interests to mandate increasing use of bio-fuels is also cause for concern about the future availablilty of suitable fuel for the current TDI engine specification.

I would also appreciate any advice about the precise nature of the problems associated with the use of bio-diesel in the TDI engine.

 

[lanmarc]

SS,
I have attached a photo of the inside of the fuel filler door that clearly shows that biodiesel is not to be used.
The manual also has the following paragraph in (at least) 2 sections of the car manual:
"Your vehicle is not suitable for use with biodeisel and must not be filled up or driven with biodiesel. If you use biodiesel fuel, the engine and fuel system could be damaged. Some diesel manufacturers blend biodiesel with diesel fuel in compliance with European Standard 590. This diesel is suitable for use in your vehicle and will not damage the engine and fuel system."

I have conducted a brief search and ES590 is mixture of 95% diesel and 5% biodiesel.

 

[MarkAlan]

You may find more extensive information here: http://tdiclub.com/

I believe they have many discussions concerning bio-diesel going on.

 

[silvershadow]

Thank you both for the information you provided and especially the TDI Club link - have hours of browsing ahead of me. It seems my current normally aspirated, mechanical fuel injected diesel 4WD will have a long period of ownership if problems arise with bio-diesel blends in the future however this vehicle is not and will never be my partner's preferred form of transport .

The situation appears to be what I expected being the combination of turbo charging, engine management system, fuel injection and emission certification constraints. I have already experienced problems with fuel quality variations in diesel fuel purchased from various city and regional service stations - fortunately with my 4WD the only effect is a reduction in hill-climbing speed, increased fuel consumption and no damage to the fuel pump/injectors. The extent of the variations encountered suggest the blended fuel contains more bio-diesel than that allowed by ES590. This could well be a problem associated with profit-maximising retailers mixing straight and bio-diesel deliveries into their tank. My local outlet guarantees 100% straight diesel at the present time but has indicated this will probably change in the future as his supply terminal does not carry stocks of bio-diesel and competition could force them to supply blended fuel to remain competitive.

It is my understanding the warranty rejection I mentioned in my original post was associated with the use of commercial bio-diesel from retail outlets and not "home-made" bio-diesel.

Just have to wait for my partner to decide on exterior colour and we can start negotiations - will still specify the TDI engine with DSG transmission and be very careful where we purchase our fuel.

Thanks again for your help which is much appreciated.

 

[SiJ2000]

Bio Diesel is a NO NO and whatever Diesel you use should be TOP Quality... In the UK, that would be ESSO, Shell or BP....

 

[silvershadow]

Bio Diesel is a NO NO and whatever Diesel you use should be TOP Quality... In the UK, that would be ESSO, Shell or BP....

The problem we face in Australia is two-pronged:-

1. Pressure from the farm lobby to mandate bio-blends for petrol [gasoline for our US readers] and diesel which are much greater than the VW/European specification. We have ethical refiners who produce high quality fuels however their advice re problems with the use and suitability of bio-blended fuel has not been highly regarded due to lobbying claiming the refiners have a vested interest in maintaining the "status quo".

2. Individual retail outlets mixing privately purchased "midnight delivery" bio-diesel with branded diesel fuel from their official supply terminal to give a bigger profit margin on each litre sold. The current level of consumer protection quality testing at the pump for diesel does not seem to be as rigorous or frequent as it is for petrol [based on my experience]. Most diesel fuel sold in Australia at present is used in engines with mechanical fuel pumps and simple injectors and bio-diesel blends so far have not created sufficent problems to highlight the lack of testing.​

The high-performance Euro-diesels have not been sold in Australia until recently due to our high-sulphur fuel however this has now changed following legislation to mandate manufacture of low-sulphur diesel. Based on the information in the TDI Engine Forum which I presume applies to engines from all manufacturers, I believe we will start to experience a series of engine problems in the immediate future asociated with variable fuel composition which will occur with all manufacturers and which will not be the fault of the owner.

It will take a series of well-documented consumer claims to convince our authorities to take appropriate action to ensure the government does not mandate unsuitable fuel blends, the vehicle manufacturers make engines and set fuel specifications which are compatible with future fuel composition and the fuel retailers know their fuel quality is likely to be tested at any time with onerous penalties for any breach of the retailer's duty of care to the purchaser.

Most first-time buyers of a modern diesel car come from a situation where they had no concern about the quality of the fuel they purchased - this is not the case for diesel fuel. The innocent victim of a warranty rejection associated with poor quality fuel has the burden of proof placed on them to ensure the fuel they buy is of the approved quality yet there is no reasonable or realistic way of achieving this in practice.

 

[SiJ2000]

I see what you mean! Here, diesel is very refined and very low sulphur! Although it is also reflected in the price!!