Wal Mart biodiesel

My local Wal Mart has a blend of B5 to B20, not specific but just a range. Can or should I use this in my 2005 Duramax? Should I use an additive with it?

If it's ASTM certified commercial bio-diesel fuel, you shouldn't have a problem, and you'll not likely need a fuel treatment this time of year.

The only Duramax engines that shouldn't use B20+ is the LMM. The higher solvent action of bio can wash cylinder walls during an active Diesel Particulate Filter regeneration. In the LMM, extra fuel is injected into each cylinder during the exhaust stroke, which is then burned in the exhaust system and DPF to oxidize the soot buildup.

The LBZ and earlier engines didn't have DPF regeneration and the latest LML engines use a 9th injector in the exhaust system to inject the extra fuel. GM approves of up to B20 for the LML because of that.

I would love to use bio on a regular basis, but there's just too much baggage associated with it. Too much risk of contamination issues/plugged filters, etc.

Bio fuels like ethanol fuels are the ones that I avoid these days and I'm not one to fuel at Wal mart regardless what the fuel is.

I break down and go to Wal mart once or twice a year for odds and ends that nobody else carries. Primarily Neutrogena lotions these days.

Hi Jim,

So is there any real-world way for LMM owners to overcome the cylinder wash problem?

In the Midwest, B-20 seems to be becoming more prevalent -- politics of the corn belt, you know. Although I have a local source for the pure stuff, when I'm traveling elsewhere in the region it's sometimes a pain to have to hunt for it, particularly if I don't pay attention and let the tank get a little too low.

Would adding extra lubricant of some type moderate the washing issue until I reached a station with B-5 or pure dino?

And of course the ever-popular question about why GM designed an engine this way when the government was steering things toward increased use of these fuel blends? Much as I've loved my GC trucks over the years, I continue to be amazed and disappointed in some of their engineering and design decisions. Oh well...

Rich,
GM is likely stating a position based on the worst possible outcomes, and a position that shields them as much as possible from warranty expenses. I can't imagine the worst happening every time B20 is used by every LMM owner.

I'd not worry about it, but I'd also not use concentrations higher than B20. If you can avoid B20 during the cooler months of the year, I'd avoid it because of the longer and more frequent DPF regens.

Hi Jim,

I was thinking along those lines, particularly when I'm towing and am running relatively high temps all the time.

Thanks for the reinforcement.