I used Shell UTF.
I visited Shell's website, and it had a way to look up which of their UTF's would work with my eMax 20S. They showed two flavors: Special-Order, Model-specific UTF, or another that was a common application for a very wide array of tractors, a truly universal UTF, available at Tractor Supply Co., Mill's Fleet Farm, etc. I bought a 5-gallon bucket of the truly universal UTF, at Mill's Fleet Farm.
I hired my indie mechanic to change it out for me. No issues since, putting 30+ hours on it after the change, using the entire hydraulics system: 3-point hitch lifting/lowering a heavy weight box loaded with stones; lifting/lowering/running a belly PTO Mower Deck; FEL; running the tractor all over my 2.5 acres, lifting/moving/pushing heavy loads. It operates normally, like it should, like it did when I bought it, prior to the fluid/filters change. Cheers!