This isn't exactly what you asked, as I am running straight veg on a second tank, but I do have an electric inline heater (in addition to coolant heating), and I have it wired to a toggle switch which is lighted as well. That gives ultimate flexibility for various fuel use. If I were to run blends, I either would not coolant heat the tank or lines at all, or I would have ball valves in the coolant lines so I could eliminate heating entirely when I wish to run diesel.

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