I had run my old 300SD for around 30k miles on a blend of about 15% diesel, 85% veggie. Engine still ran perfect when I sold it. But now that I have a W124 style 6 cylindar that I want to drive for a long time, I have a 2 tank setup.

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87 300D - Running on Veggie oil; 260,000 plus miles; Original #14 head