Toro HYPR-OIL mixed with 15w50 YAY or NAY?

Our Toro model 74451 zero turn currently has 15.9 hours on it. The service interval suggests changing the hydraulic system filters and fluid after the first 75 hours, so we are a bit away from this service yet. After the initial 75 hour service, the recommended interval is every 500 hours when using Toro HYPR-OIL 500, or every 250 hours if using Mobile 1 15w50. So, the Toro oil doubles the service interval by 250 hours! Or so they claim!?!?

Our hydraulic reservoir is a bit low and we need to top it off so that it is right at the cold line when cold. Is it perfectly acceptable to add 15w50 to what I would assume would be the original Toro HYPR-OIL 500, since the machine was bought new from the local dealer? Or should we only add the Toro HYPR-OIL to top it off since the hydraulic system has never been drained?

Secondly, is using Mobil 1 15w50 a MUST or will any other brand's 15w50 oil suffice? The manual doesn't suggest using Mobile 1 FULL SYNTHETIC for 15w50. It only states "Mobil 1 15w50 fluid." I assume they are referring to regular motor oil, correct?

Thank you!

I have an exmark which is similar to the toro hydro’s. It came with mobile one in it....non synthetic. After a couple years they said you must switch to the toro oil because mobile one changed their formula. I converted over....drained system and filled with toro oil. I’ve used toro.s oil ever since but have heard others never converted. With the price of toro’s oil I will switch back to mobile one if I have to drain system again. Not sure about mixing them....toro’s oil is green in color.....but could be a dye?

It is hard to tell what color it is in the reservoir. Whatever it is, it looks to be dark :wink:

I would ASSUME this Toro machine would be shipped with Toro oil in the hydraulic system. Seems logical?

Is the 15w50 the manual refers to, engine oil? Nothing special I would assume? And why are they specifying Mobil 1, is it because of a financial agreement or is their formula the only brand that will work? Say, not Supertech or Castrol or Pennzoil or Valvoline?

This is an old thread, back in April 2021 my Dad ran over a sign post that the crazy methed up tenant in the adjacent property installed as a property marker, slicing open the left side hydro filter. So I ended up draining both hydros, installing new filters, and using the specified Hypr-Oil as the manual called for. Essentially the break-in service which was called for the hydros was performed quite early at only 36.1 hours of run time. I went out there to mark the sign post with some brightly colored neon paint at which point I too was harassed for daring to mess with the holy grail of a sharp sign post installed by junkies.