Ok, thanks, winston1
I see that John Deere 303 oil is no longer sold and its replacement must be John Deere HY-GARD.
Is this correct?
I found this online store in Spain where they sell it:
https://compralubricantes.com/aceites-multifuncionales/john-deere-hy-gard_1317.html#/10-capacidad-20_lt