JD303 vs. Hy-Gard

I didn't want to ask this question, but after researching other forums and internet sites I still don't know for sure: Is a store-brand 303 hydraulic oil a good substitute for JD Hy-Gard hydraulic oil? The boss bought a couple buckets of the off-brand 303 oil because it is a lot less expensive than Hy-Gard. But if it is not a good idea to use it in my 2955, I'd like to know. On one site, a member said that Hy-Gard is just JD303 renamed. True?