Biodiesel problem in 2003 VW Jetta?

I was happily running my Jetta on mostly biodiesel (refined from recycled cooking oil.) I like the idea of reducing American dependence on foreign oil, as well as encouraging more deep fat frying, I guess. I often do mix petro and bio. After running the car about 40,000 miles (96,000 total mileage) the fuel injector pump failed. I got it replaced, and after 6,000 more miles, the new pump failed. VW refuses to honor their 1-year, 12,000 mile warranty (giving them the opportunity to sell another thousand dollar pump.) They had apparently noticed the aroma of french fries, and declared the warranty void. It could be an opinion about my diet, or my choice of fuels. The people who sell the biofuel say that a higher concentration of biofuel is good for the seals, and the people who sell the VW say the opposite. I am fighting VW about this.
What gives? Anybody know? Anybody with experience with this scenario?

Who are the people selling you the bioD? Or are you homebrewing?

I buy the biodiesel from Biodiesel Oasis in Berkeley. Here’s their web address:

Well they claim to sell “ASTM quality” bioD. Do they actually have ASTM labs to show you (and VW)?

The pump failure may not be seal related, that is an assumption.

What % bioD do you run?

How often do you change your fuel filter and have you checked for water in the filter (drain at bottom of filter)?

They mention DFIS on their site, they were the first shop in the USA authorised to rebuild the TDI VE pumps (A shop in Missisauga Canada was afew years ahead of them). I would send the pump to them for diagnosis of the failure cause.

Good luck, it will be a uphill battle w/VW.

There are so many potential issues with small batch bioD that it would make for a very long post. If you have not done so already you may want to visit the BioD section of the forums at

Most car manufacturers explicitly forbid greater than a certain (low) % biodiesel, so VW has the right to refuse. Of course the biodiesel seller will disagree.

Was the “New” pump they installed new or “Rebuilt”?? But look at it this way…All that money you saved by using fry oil is now in V.W.'s pocket, not yours…And more to come…

This problem is more than likely caused by the fuel so fingers should not be pointed at the pump and VW itself.

I note the site you provided references that the fuel is “ASTM quality”. That could be a word game because that blurb does not necessarily mean the fuel meets any standard at all.

Most diesel engine manufacturers do not recommend more than a 20% blend of bio diesel to petroleum diesel or B20. The reason? A higher concentration of bio diesel can damage injector pumps and/or injectors.


Two injection pumps have died now due to McDonald’s aged french fry oil so it may be time to consider running what the car was designed to run on in the first place.

Are you running biodiesel or waste vegetable oil (WVO)? If your exhaust smells like French fries you must be running WVO. Biodiesel should not have that smell. You should not be running WVO at all, only biodiesel.

For biodiesel, the ASTM standards that are pertinent are:
ASTMD6751 – neat biodiesel as a blend stock
ASTM D7467 – Blends of 5% to 20% biodiesel with petroleum diesel.
Blends less than B5 are covered in ASTM D975, which the standard for diesel fuel.
If your provider does not certify the fuel, I would not use it.

VW will not honor your warranty because biodiesel is a strong solvent, and in higher blend rations (greater than 20%) can seriously degrade the seals in the pump.

You would be better off posting this question on one of the biodiesel and/or WVO forums.