We pulled in and then through the Chevron as we saw that they only offered diesel with a bio-diesel mix of 15%, 3x more then than the 5% mix of what VW (outside of Illinois) and many other manufacturers allow. So, not wanting to have our car's existing warranty possibly voided unnecessarily we continued on to find a station with no more than 5% bio diesel mix. We than drove into the Astro station, and again we drove out as we saw that all they had was again the same lousy 15% mix. My memory kicked in and I remembered to try Love's Truck Stop because I recalled that they didn't have more than a 5% bio diesel mix the last time I went through; but as luck would have it they were sadly (very) closed, from a previous fire. I found this unbelievable and very interesting because I typically fuel up at Fred Meyer Fuel pumps, so I didn't realize that +5% bio-diesel mixed fuels were so prevalent, and the only choice in Winston. Previous to this day when I had seen a bio blend in other cities it was typically either 20% or nothing. I wouldn't have previously believed that 15% would be the only choice in this town of at least 3 (out of formerly 1 more) stations especially because, to me at least it really is the worst mix scenario. As I mentioned to one of the fuel attendants, at 20% the state of Oregon kicks in a savings off the fuel tax that is quite tempting, in an effort to get you to go 20%, but at 15% mix you get about the same mix, which will still possibly void your engine warranty, only without any incentives that make it any cheaper then straight diesel.
I know most people who drive late model diesels haven't read the small print in their owners manuals (who does?), so most fuel up without a care. However there are good reasons on these limitations and there are good reasons why it pays to be informed. One main reason why VW and other manufacturers set bio diesel limits with regards to warranty coverage is because bio-diesel has a well known tendency to absorb water as it sits in the tank. Water in diesel fuel is not a good thing, as it is said to possibly increase the water level in your engine oil, which requires more frequent oil changes.This can be especially bad with vehicles that call for longer oil change intervals, such as VW which recommends for example that my Jetta TDi oil is changed every 10,000 miles with synthetic oil. If I did use bio diesel I would need to check my oil level more often and change the oil more often or possibly face very, very costly engine repairs, excluded and now voiding the remaining warranty.
If you ever find yourself in a similar situation as I did and you need to refuel with a bio-diesel mix VW recomends that you chose a place that sells lots of diesel, such as one close to the freeway, as more water will accumulate in the storage tanks as time passes. As luck would have it, I had heard that the Shell station's diesel business in Winston had apparently increased from one tanker a month to a fuel tanker delivery every week, about the same time that the truck stop across the street burned down. Just buy enough to get you comfortably to a station that offers straight diesel or at least less than 5%, or be checking your oil more often!
VW TDi owners in Illinois may point out that they are a bit more special then the rest of us as they are allowed to use a higher bio-diesel mix (of 20% I believe) without risking voiding the warranty. I was told that this is because more stations offer the 20% mix blend than do not, possibly due to a state mandate.