i had a leaky jack curbside rear
i added 'blue devil hydraulic sealer' to the jack reservoir
instructions say run equipment for 2 hours
i did not play with the jacks for 2 hours
i did take 10-15 minutes raising and lowering the rear jacks
to circulate fluid
we fulltime, in a few days the leaked stopped
occasionally if i fully extend/stress that jack, i will need to top off the fluid, sometimes i use pure tranny fluid , some times a 50/50 mix with blue devil, its a top up, so it doesn't affect the system percentage too much
blue devil says can be as much a 25% of fluid
a google search found it on amazon
beats buying a new jack