i run my second tank wvo fuel through a heat exchanger made from 1" heater hose with brass fittings on each end with 1/2" fitting on the side of each end for the heater hose to clamp onto. so from the engine it goes to and from my heat exchanger prior to the heater core..
in cold climates you may want to run the system in parallel. so the heater will work better. as for the 3/8" copper tube that runs through the heater hose, with wvo in it. the ends of the copper tube and brass fittings are a type of fitting that uses a copper ring and threaded cap that squeezes the ring to seal it. don't know the proper name for the fitting... i use a plastic fuel line from the tank to the heat exchanger.... from the heat exchanger to the fuel filter, then to a tank switching valve... which has extra fitting for the return fuel line. so the return fuel returns to the proper tank... some fuel will return to the wrong tank during line purging when switching. not enough to worry about..
i have the tank switching valve wired in with a engine block temp sender. that grounds when the block gets to 160'f. so when i turn on the wvo, the tank won't switch until the engine is up to 160'f...
i just have to remember to turn the switch off, so i use diesel a while before shut down..
having the filter with warm fuel passing through it, cleans minor accumulation of thicker fats. which burn very well when warm and thinned out...

i usually pick up a couple mpg on wvo. and i loose 80-90% of my exhaust smoke.. non-turbo as it was built, by ford.. (mazda sourced and built perkins diesel)
my friends call my ranger the chicken fried truck, or the french fry machine..
it will make you get the munchies, until you get used to the smell..
i strain my used deep fry oil through old clothing, into a old water tank with a drain valve in the bottom and the top cut off. i pump from this first stage of oil cleaning through two 10 micron house h2o filters. hooked up in parallel so i have less pressure buildup as they collect particles... on the bottom of the fuel oil storage tank i have a water heater element hooked up with a timer and temp limit switch... in the winter i heat the tank to 100'f. as i run the oil from the bottom of the tank through the filters and back to the tank for a hour or two. or whenever i think of it while working in the shop... keeps things mixed up... the system is set up for filling my truck as well. using the 1" water pump mounted below the fuel oil tank.through the two filters then to the nozzle. which is what you can buy at the farm store. looks just like the nozzle at a gas station...
i buy my 10 micron house h2o filters at china-mart (wall-mart) or ace hardware.
the factory filter on the truck is 12 micron, so it stays clean quit a while...i have two separate filters on my truck one for each fuel.. so i don't have to wait for fuel to change in the filter, while changing tanks... i put the changeover valve just before the fuel pump/injection pump. after the two separate fuel filters.. as my system is a draw type of system. no boost pumps..
while in the northwest during the winter, i do have to blend the wvo with #2 diesel to keep flow and burn proper. during summer in the south i can run 50% wvo in the diesel tank with no noted ill effects on the engine. only time will tell...
i have noted that i need to have my injectors cleaned. the truck has over 250,000 miles on it. with 75,000 of those miles using wvo, a bit of wmo and some atf.. the little engine does not like wmo or any synthetic oils, as the engine doesn't burn the oil hot enough for a clean burn... you would think 21:1 compression would be enough...
the injectors were needing cleaned b4 i bought the truck. but the problem with cold starts is becoming noticeable, on real cold days... so i imagine the pattern has changed some...as has the amount of smoke increased when during pure diesel...
any comments or questions, give me a note or post here.
cc