Re. bioDiesel in an R32 TDI swap
Off topic but I can't resist.
When I blow up the 3.2 VR6 and put a TDI in the R, I will do it with the intention of running bioDiesel. I'll have success, I reason, because after 10 years of running it in as high a blend as possible, I've figured out a few things. (Context: I sold biodiesel for 3 years commercially and I have worked on TDIs (not to the extent of either of you, by any means) for 10 years, with the help of oldpoopie and others here, I must add.)
I am sensitive to fuel flow restrictions. I drive more attentively than most and I notice this and know what's happening. When it gets cold and I have over B20 in the tank (I work to avoid this and watch weather and top off on D2 when conditions dictate), I usually detect the issue and change the fuel filter soon thereafter.
My biodiesel producer supplier (locally) filters the fuel to 2 microns and insists on stringent water separation and methanol recovery. These are key.
I have a PCV bypass/oil dropout set up on one and no EGR on the Toyota. This certainly helps with the intake manifold drama which eases wear and tear on the other interconnected systems.
I drive all three cars harder than most and they rev higher than most. Not stupid high or to redline often, but they breathe and cycle. I let the car cool down after driving workouts to prevent injector coking.
I've cleaned the fuel tank pickup on my (and others') cars. Bad D2 or bio, I don't know.
This is also significant - I don't let D2 sit in the tank (or IP) without bio mixed in. Even in minus 17F, there's 5% bio in the tank helping to reduce that IP seal shrinkage. Yes, bio swells seals, and yes, switching from B100 to B-zero is hard on the IP. Lots of people do this, again, being less particular than I am. Viton internals from DFIS may get me the 2nd 180,000 miles on the '99.5. Time will tell. I got 180,000 on the original IP conscientiously using seasonally, temperature appropriate bio blends. 276k on the '99.5 and running strong. Original turbo.
All this is to say that driving style and attentiveness matters as you and everyone on here knows.
It's important to remember that original (and now very dated) data on bioDiesel comes from a 12.7L 1991 Detroit Diesel C Series 60, four-stroke, turbocharged, inline six-cylinder. I'd love to see '03 TDI data.
There is a learning curve with bio, especially in cold climates. I wish there wasn't, but there is.
You both make valid points. I assert that the average Portlandian, putting in whatever bio blend, straight D2 at times, never exceeding 2500 rpm, primarily city driving, inattentive to cold, the car's performance, and regular maintenance, should not build an RTDI.
It is worth noting that bioDiesel blends higher than B20 are now illegal in CA, thanks to the Alternative Diesel Fuel legislation pushed through by big oil (Neste and others) and
probably because of old emissions data.
http://www.arb.ca.gov/fuels/adf/20151222adffaq.pdf
and
http://www.arb.ca.gov/regact/2015/adf2015/adffinalregorder.pdf
The law includes language allowing what's called B20 to actually be B6-B20. Amazing. Bummer.
FWIW