I'm betting the sight glass in my old L3200 was plastic. But it never had any staining issues from the JD dye.As long as the sight glass was actually glass, I won't be concerned with adding a dye. But if this is plastic of sorts, then I would stay away from dyes. The dye could permanently stain the plastic and make it even more difficult to read. Now, if you only have a dipstick then the dye would be great for that.
Set the dipstick on paper & it will stain the paper where there is oil. You have to wipe the dipstick off then dip it again to get a good reading. Works good for me for now to avoid buying another bottle of dye.I could not read the transmission dipstick level on my Kubota so I added a small amount of used engine oil, which darkened it enough to see easy. I service the transmission at the recommended hours, so I can not see any harm from the oil.
I used the JD dye in my hydro Kubota!Worked great,almost impossible to see on the dip stick without it.
Note;when I brought it in for service the Kubota tech had thought I had put automatic transmission fluid in my hydro.Used two bottles,one may have been enough.Around $5.00 ea.
The JD dye is actually red.We really need to lean on Kubota and have them come up with an Orange colored dye, putting Green in a Kubota is just wrong.
David