Diffrence between expensive and cheap hydraulic oil?

Hey everyone, Been in the earth moving game for a few years but have always been lucky to work for moneys no object company's with the best of everything. Now I'm out on my own things are different.

What I was wondering was how much of a difference is there between expensive and just normal hydro oil? I'm sick of paying $170 aud for 20L Drum, So I'm looking at getting a 202L drum. Some brands are in excess of $1500 a drum but then there's a few that Ive noticed on a local page for around...

Diffrence between expensive and cheap hydraulic oil?

Diffrence between expensive and cheap hydraulic oil?