MileGrinder

Starting a new thread as previous ones are damned old and unlikely to be seen.
I'm in far northern Calif a couple hours from Oregon border. Not much bio availability up here other than at commercial pumps at TA Travel Center a few minutes south of Redding. I've been running different combos of bio based on availability since I got the truck 15 years ago this month, coincidentally, including B100 from Four Corners Recycling near Bozeman when I visited my kid up there. Never a problem except for a bad load at a hippie co-op outfit in Phoenix, OR, no longer there (over ten years ago). Fixing that cost me a bit.
Anyway, I was online again searching for new sources and ran across a couple of forums that advised keeping the 3gen Cummins 5.9 away from any biodiesel. I'm not a gear-head, but the gist of it was it will eventually gum up the fuel delivery system, costing the owner a lot of $$$ to repair. No one specified whether this is dependent on the mixture or using it in any config (B5, B20, B99, whatever).
Since the threads on here are so old, I'm wondering if 2003-07 5.9L owners have just moved away from bio. I use it because I like the idea of reusing something (WVO) to take demand off a market for a product whose price just doesn't seem to fall that much.
Any insight on whether I should be avoiding bio for this particular engine/generation? Right now I'm filling up at the TA with B20 when I can get down there.

Fordzilla

When I had my 2003 I used B20 in it often because it was a little cheaper...I never had a problem, and fuel mileage was consistent...I haven't noticed bio hereabouts since I got my 2009......Ben

marathon

The problem I've heard is that Bio is a better solvent than straight dino. If you've never used Bio then suddenly use a high %Bio, it will loosen all the accumulated crud in the fuel system and clog everything.

Danavilla

My '06 owner's manual clearly specified that no biofuel above B05 was to be used. I travelled throughout the US and found many instances where nothing other than B20 sold. As a result I often ran B20. The first couple tanks clogged filters so bad I kept a couple extra so I could change beside the road or in rest stops or campgrounds. Once most of the crud loosened by the Bio was cleaned out clogged filter problems diminished but I still kept a couple spare, just in case. I just sold the truck to my grandson and advised him of the potential issue. He is a diesel mechanic so I'm sure he can deal with it.

Mikey-KE7LBB

I've been making my own for a while, and smile whenever I drive past a fuel station and see the price I don't have to pay. Sure there are some cons, but they are pretty minimal if the fuel has been processed correctly. The only real issue I've had with running B100 in my '09 is when the truck stop runs out of used cooking oil!