Making their own?  Biodiesel?  I would be interested in knowing how long
their seals last. Especially the injector pump.
<<lots-o-snips>>
Doug

Doug,

 The seals last a very long time, as do synthetic fuel hoses.  Natural
rubber will deteriorate from the fuel.  Biodiesel is approved by most of the
world's OEMs in 5% concentrations (B5).  Concentrations above 50% (B50) can
lead to corrosion in injection equipment, deposits in injectors, among other
issues.  Washing removes extra alcohol, excess lye, and any remaining soaps
from the fuel.  Biodiesel attracts water, and is more susceptible to
oxidation from the higher heats and pressures of modern fuel injectors.

 This, and waste veggie oil, work better in old Benzes because of the lower
injection pressures and larger injector holes.  The move to unit injectors
and then common-rail carries higher injection pressures and a higher
quantity of smaller injector orfices.

 The hydroprocessing used to remove sulfur from diesel fuel damages the
fuel's lubricity, and removes aromatics.  The older fuels with higher
aromatic contents caused seal swelling.  The 'seal shrinking'/injection
equipment leaks that happen each time the fuel changes are caused by the
seals returning to near their normal size.  Biodiesel can be used as a
lubricity additive (2% is all that's needed to exceed manufacturer's
requests - which are better than the current diesel fuel ASTM lubricity
requirement).  It can also be used as a 'seal swelling agent' to get more
life from older injection equipment.

 I just replaced the injection pump in my '97 VW TDI with 340,000 miles on
it.  San Antonio ULSD wasn't enough to keep the seals happy and they started
to leak last May.  I drove north to Superior, Wisconsin, across to Mt
Rushmore, and back last May -- no leaks while using either B20 or 'low
sulfur fuel' (500PPM).  The leaks started again once I returned to San
Antonio and started on my 2nd tank of fuel.

I have current info from Lubrizol and Infineum on biofuel concerns from an
oil and fuel additive supplier viewpoint, and vehicle OEM supplier
viewpoint, if anyone's interested.

Andy Hecker
'96 and '97 VW TDIs
Biodiesel - home made and ASTM commercial - from B20 thru B100
Oil and fuel additive dealer



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