mine is mostly lucas p/s fluid with a stop-leak additive. If its driven every day I have no issues, it works-its quiet, no leakage. If I park it for awhile (over a week) it starts leaking out, I think from the pitman shaft on the steering box, if it were to sit for a few months without being drove it will be down enough that you cant see it at all in the reservoir on the pump. But if driven daily it doesnt seem to leak at all. But it is a ‘94 and as far as I know its all original with 160K + on the “clock”. Id think any hydraulic fluid would work in a power steering system, I might purge my system and try 303 tractor hydraulic fluid just for the heck of it, worst it can do is be noisy & leak more. I have a manual box and have considered swapping to manual steering but not sure Id like that except for having less crap under the hood.