At the top of the page is a sticky that regards WVO use. One quart to a full tank of diesel wouldn't do any harm but I'd check your filters just be to sure. Depending on where you live, it might not be good to add a whole lot more if it gets cold. I'm not a blender because its my preference to run a separate, heated system. I'm not saying that there's anything wrong with blending, I just prefer the heated, dual tank system. I think one quart might make it run a bit quieter but I'm not sure. I'm sure a blender will chime in soon.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo