Me wrote:
I don't have any hydraulic jack oil and my cheapo jack leaks like a
sieve.
What do you suggest is best replacement for the oil?

auto transmission fluid?
brake fluid?
power steering fluid?
motor oil?

10W30

Rule 1: Try 10W30, If 10W30 does not work apply rule 2
Rule 2: Try WD40.
Rule 3: Give rule 1 another try