I would not add anything to a 2UZ other than quality fully synthetic (non high mileage) oil in 5w30 or if in a really warm climate something with a bumped up winter weight like a 10w or 15w.
There is absolutely no need to baby a 2UZ and adding things to the crankcase is unnecessary. If you want to do something to confirm this, many of us have pulled an oil sample at a known interval (you need to know what you put in and how many miles are on it for it to be a good test) and send the sample into blackstone labs for a $25 oil analysis.
Great peace of mind and in my case has saved me money in the long run - good oil isn't cheap, especially lately. I have had multiple 2UZ's and found I was literally throwing away perfect oil by changing it at 3-5k and can push out at least 2x that even on the severe duty schedule with towing, offroading, idling, etc.
Look up the pictures of most folks valve cover gasket jobs and you will see just how clean the valvetrain stays on these things if you do oil services on time. Even if the PO pushed intervals too far, just stay on top of doing your intervals on time and you'll be good.
That being said, I had Jeeps in high school and it was common to just add a half a quart of ATF to the crank case to free up sticky valves, drive 50 miles or so and then drain the oil to get the junk out. But no need on these motors.