I know a chap here who has run his HZ on solid fat for 15 years, and never had a spanner on the engine.
Of course it has all heated lines, and heated tank, he does 15 km before he changes over, has to open the bonnet to swap fuels. He stopped her on fat once, and got stuck into it with a blow torch and got her started again.
This is not hearsay, I know him and his vehicle personally.
So it can be done, just have to heat it all. Animal fat is a good fuel, I have no doubt of that, just don't ever let the motor get cold without purging on diesel.
I cold upflo into two 100lb propane bottles in series with a vacuum in them, and pump with a little eBay pump into a 1 micron whole house filter wrapped with a dozen turns of bed sheet. With the outlet of the pump throttled to slow the flo, the oil has time to heat in the pump to flo thru the filter. I let my 20lt drums settle first and lower a pickup tube into the oil until I start to get the animal fat. I have a gauze filter after the drum pickup, and a little gauze filter on the drum pickup.
Pouring oil thru filter socks, never done it, forget the messy idea.
I am amazed to see water boiling out of the oil like lemonade in the filter when it hits the vacuum, and the outlet of the vac pump vents water vapour, you can see it.
I would not have believed this much water could be in clear settled oil. Starting near the bottom of the drum where there is a little animal fat shows the most water boiling from the oil, as the level drops there is less water. I don't mind a little animal fat in my fuel, it all burns and I heat the oil as it leaves the tank, and use another I micron whole house filter wound with bed sheet in the Hiace for her wvo filter, and a fuel pump at the tank after the heater.
I strictly purge back to diesel before stopping for any period other than a shop stop, they don't like starting on oil.
I have done 1000's (and 1000's) of km on wvo in the Hiace and Hilux, both vehicles near 30 years old, Hiace turns 30 next year. I have (bought home yesterday) a factory fitted turbo motor for her. We can do 5000km in one trip without buying fuel, take 500 lt with us, now that's heavy for the little 2.4, so needs the turbo.
Seal the filter ends with silicon before you use them to stop the oil short flowing around the ends
Wvo works so well in these old indirect injection Toyota's that I have no intention of ever making bio, why bother when wvo works so well.
I have been a blender when I started, but now a firm believer in two tanks. I have never mixed petrol with oil.