I think and this is just my opinion. Running any alternative fuel in your deuce other than diesel is most likely going to end in premature engine failure and components. How long depends upon a variety of issues. The military's need for a multifuel engine basically comes out of WWII. Most American engines of that era for tactical trucks were gas powered. Being that your fighting a war overseas the logistical nightmare of supplying proper octane fuel to a fighting advancing military and sometimes retreating was monumental. So in order to better utilize your military assests, it would be great if that advancing military had a constant source of fuel (any fuel) to keep them going. Remember Rommels Afrika corps (Germany) had a very hard time keeping their tanks resupplied with diesel,if only they had multifuel back then. The multifuel deuces or engines that you own today are born out of the mistakes or advancing technology of WWII.
The problem with multifuel engines is not that it won't burn just about anything that is flammable. It is the fuel sources themselves which will eventually destroy your engine. The multifuel diesel has a compression ratio of about 22:1 atmospheres. Diesels volatility is much lower than gas so you have to put the squeeze on it to ignite. As you compress the diesel you create friction which creates heat which inturn vaporizes the fuel mixture for proper combustion across the dished piston. The multifuel was designed to run diesel as a first fuel source "the preferred fuel" whenever possible, also because it was already readily available. Only use alternative in extreme emergencies or situations like being on a battlefield and running out of fuel.
Oh wait theres a disabled jeep,truck,etc with some gas in it, drain the crankcase and mix some used motor oil with it for pump lubrication. Then once out of harms way replenish with diesel. That was the concept,never to switch over to any other fuel source for an extended amount of time. Again the devil is in the details. The diesel runs at higher temps,therefore a diesel is built with looser tolerances. At first startup if you have a tuned ear and especially in colder climates it sounds as if the engine is going to knock itself apart but after a couple minutes warming up the gaps start to close and tighten and it becomes more efficient and responsive. It's those first minutes that are critical to really any engine especially diesels as there is a lot of crankcase blowby.
This is where the alternative fuels that are just being filtered come into play. You are filtering out the particles so it's passes through the fuel and IP pump and injectors. But are any chemical analysis being done on the chemistry of the alternative fuel your burning. I chance a guess and say no. Theres some nasty chemistry in WMO/WVO used brake,hydraulic,old burnt transmission fluid and gear oil. Diesel comes right from the refinery and has additives in it for proper cleaning and combustion. Even then the engines need rebuilds at certain intervals. Putting something other than preferred fuel into your engine and your increasing the likelyhood of premature failure of lower end engine components (bearings). Also a lighter fuel than diesel will find it's way into your crankcase faster and also wash your cyclinder walls down of oil (scoring of cyclinder walls). Just condensation in your crankcase from sitting for a while will etch you crank, rod,cam bearings not to mention antifreeze if it's gets in from a blown head gasket. Most multifuels were already rebuilt at some time,so it's safe to say that most deuces out there already have high hrs and mileage on the truck,which is engine wear. If you have a tired engine already you will be speeding up the process. And don't believe the hobbs meter or odometer they are easily dis and reconnected which misleads you into thinking that your truck is low hrs and mileage.
I don't think the military ever used the multifuel as some people are now using it to burn alternative fuels. I was in the USMC back in the early 80's and we always ran diesel,nothing else. As a military asset it's nice to have when you need it (tactical situation) but don't abuse it. You guy's are now the guinea pigs,it's your vehicle. Just keep checking your oil quality in your crankcase and look for signs of other than what should be normal oil texture,viscoscity,smell. Probably help to do more frequent oil changes too. Hey at almost 24 qts oil change,you can just turn around and dump it back into your tank. You can get yourself on your own list of people that you pickup used oil from. And if your engine sounds like it's going to grenade itself,well parts and trucks are still pretty cheap right now,stimulate the economy. A penny isn't worth anything anymore,so it's not worth my time to give 2 cents. So heres my "Just my $25.00