Hello, I can't seem to find the exact size of the fuel lines, any ideas? appear to be 5/16 id maybe? I am going to add a tee for the supply and return under the hood so I can add a small 1 gallon tank under the hood. I will then have a larger tank push the wvo to the smaller tank under the hood. I have electrical heaters for the underhood tank that operate off 12 volts and get it nice and toasty. I will plug in the car at home and use it to pre heat the wvo to operating temp before I go on a trip. It should heat up real fast considering it'll be a 1 gallon tank, then I can use less diesel! I was going to use ball valves for starting out, then use solenoids if all goes well. With my small tank I can position it to where the lift pump will practically be fed WVO, so I should not need an additional electrical pump, correct? but if I go, what PSI should I get?

I am going to be doing a cold upflow & filter down to atleast 1 micron, and always travel with spare filters in my car. If I can collect enough oil from my two planned sources I will add a warm upflow to the initial filtering stage aswell. Let me know what you guys think

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1984 300sd auto with 246,000 miles

5/16"ID hose will fit on your steel lines.

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I have been a big user of Pex line as fuel line. Even on my 62 psi 2005 CDI mercedes. My old 1985 300d used all pex lines for both diesel and veg side. I used no hose clamps and the stuff was 30 cents per foot. I heated it with a blow torch and pushed it onto the fittings for a perfect fit that never leaked air.

You sound like you are on a budget. You might consider the pex. Also consider just buying a good greasecar switching valve. You can use just one and loop it and make the second valve the 3 way ball valve the one for the return to tank. That way you only need one three way ball valve. Those are not cheap if you think they were, but they are less than the electric ones.

But first I might add that you start filtering long before you start converting. Two tank conversions are actually cheap and easy compared to a good filtering system. I was atleast 3 vehicle in before I had a truely good filtering system.