Injector cleaners / decarboniser.

Work the snot out of it, then you will know about how much oil it burns as well as any misfire, slobbering etc.

A set of injectors would be around $120.

ATF in fuel is someone's old idea. Never thought that transmission fluid was made to not burn. If you want a fix in a can try a super concentrated dose of dieselkleen gray bottle. Out board 2cycle oil. Not motor cycle oil but. OUTBOARD 2 cycle (tc-w3) oil is made to burn cold and keep things clean. I have taken old equipment that smoked and over time they run like new. Dieselkleen once. Outboard oil every time 200-1 mix. I got this info from a guy who actually tested atf against out board oil. There's picktures on the web somewhere if you look em up.

I buy my outboard fuel from Walmart. Run it in my Dodge cummins. Raises. cetane level in fuel. Improves milage

before you go down the list of all these magic potions, I was always led to believe white smoke means that some air is in the mix and this is even more the case if it ran fine the time before
Perhaps crack some injector lines for a few minutes on each injector and see if it improves before adding stuff to the fuel that isnt meant to be there

On a lot of Cats gear there is no return line to the tank and as such air can get trapped in the injector line end


Paul

There should be no return line on any U series tractor. Couple of drain/tell tale lines on left front corner of the block,.but these don't normally leak enough that someone would bother to route one back into the fuel supply to the lift pump.