Biodiesel use - after years of use...
I've been using Biodiesel for several years in a variety of Diesels. Prior to this I blended filtered WVO, have even used used motor oil... I've also learned that filters can clog pretty quick...
Problem you'll typically encounter with either is trouble with seals dissolving with both WVO and BioDiesel. Depending on how well your BioDiesel is processed will determine if you will have troubles that way. I've had to replace a few o-rings and the high pressure seals in my '91 300D. Other Diesels like a 1.6L Caddy I had to do nothing. GM 6.2 and 6.5 Diesels required replacing anything rubber in the system and an aux pump... ugly messes.
THEN ON MY TDI... (which is sitting dead in my shop waiting for parts maybe because of the 1st tank of BioDiesel)
on my 2003 Jetta TDI on the first full tank of BioDiesel I got error codes, hammering sound from my IP and loss of power... I pulled the injectors, two were bad... replaced the filter... cleared the code... a couple days later, hammering started, code P0252 reappeared. Talked to the Diesel shop, we determined a Diesel Purge might help it did... for about a day... then it started again... DP, one day... DP, 1/2 a mile... Got the triangle tool, pulled the pump apart, cleaned the Fuel Metering stuff... worked great for about 15 miles... then hammering in the IP, loss of power (not revs though) and P0252 and P0251 (ah ha! the metering code!)
Here's picture of the insides for those of you that have no courage... or don't live life on the edge: (if you're faint of heart, don't look... if you like this sort of things will be happy to share the links to the inside of my Nikon D300)
Bottom line, I can not say with certainty that this would have happened had I not had a full, 100% BioDiesel tank or not... But then again, this TDI will not see BioDiesel again... no point at 40-50mpg... will use it in my other Diesels.
My 300D really lost power on that batch of BioDiesel so I suspect it was bad, I also had to change the filters on it. This was the first batch from a new co-op/friend... perhaps my last.
Anyway, watch for rubber parts dissolving, loss of power, lower fuel economy, but less costs (typically), nicer exhaust smell and the feeling like you're getting over on the system... i.e. no fuel taxes! We like to think it's free, but one spends a lot of time lugging cubies and buckets around, my shop floor is gross...
Oh, BTW, that metering control part... it retails for about $1100 if you buy it from an injection shop, their cost is $500. The dealer doesn't sell it, only the pump, retail prices is $1402.
I'm planning on buying a rebuilt pump from http://DieselVW.com
unless one of you tells me I shouldn't. I think I'm going to spend the extra $100 for the full Bosch pump... the aftermarket part pump is $700 minus $300 core = $400.
I've gone as far as I can with this without replacing the IP... Christmas break project...
BioDiesel usually results in lower power and mileage... on my '91 300D in town mileage is typically 28-30mpg,
with BD it can be as low as 23, typically 26 or so... and the car can be quite gutless. Smells better though.
The exhaust on the TDI was much nicer with BioDiesel.
I'm building an '83 J10 Stepside with a Scout Diesel drivetrain, ran an SD33 with 100% BioDiesel for over a year, NO PROBLEMS whatsoever... my '91 300D has been using it for years with mileage loss and power loss but no other issues... except for an o-ring in the fuel heater and the high pressure seals, which I can do in the car in very little time, again, faint of heart, don't look: http://johnmeister.com/DieselBenz/TECH/124-series/Pressure-Valve-Seal-Replacement-2010/ALL.html